Method and apparatus for processing three-dimensional images

ABSTRACT

A three-dimensional sense adjusting unit displays three-dimensional images to a user. If a displayed reaches a limit of parallax, the user responds to the three-dimensional sense adjusting unit. According to acquired appropriate parallax information, a parallax control unit generates parallax images to realize the appropriate parallax in the subsequent stereo display. The control of parallaxes is realized by optimally setting camera parameters by going back to three-dimensional data. Functions to realize the appropriate parallax are made into and presented by a library.

RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.10/949,528, filed on Sep. 27, 2004, which is a continuation ofInternational Application PCT/JP03/03791, filed on Mar. 27, 2003,claiming priority of Japanese Patent Application Nos. 2002-087493,2002-087494, 2002-087495, 2002-087496, 2002-087497, all filed on Mar.27, 2002, and Japanese Patent Application Nos. 2003-003761 and2003-003763, all filed on Jan. 9, 2003, the entire contents of each ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stereo image processing technology,and it particularly relates to method and apparatus for producing ordisplaying stereo images based on parallax images.

2. Description of the Related Art

In recent years, inadequacy of network infrastructure has often been anissue, but in this time of transition toward broadband, it is rather theinadequacy in the kind and number of contents utilizing broadband thatis drawing more of our attention. Images have always been the mostimportant means of expression, but most of the attempts so far have beenat improving the quality of display or data compression ratio. Incontrast, technical attempts at expanding the possibilities ofexpression itself seem to be falling behind.

Under such circumstances, three-dimensional image display (hereinafterreferred to simply as “3D display”) has been studied in various mannersand has found practical applications in somewhat limited markets, whichinclude uses in the theater or ones with the help of special displaydevices. From now on, it is expected that the research and developmentin this area may further accelerate toward the offering of contents fullof realism and presence and the times may come when individual usersenjoy 3D display at home.

Also, 3D display is something expected to gain its popularity in theyears ahead, and for that reason too, forms of display that could not beimagined from the current display devices are being proposed. Forexample, a technology has been disclosed whereby a selected partialimage of a two-dimensional image is displayed three-dimensionally (See,for example, Reference (1) in the following Related Art List).

RELATED ART LIST

-   (1) Japanese Patent Application Laid-Open No. Hei11-39507.

In such a trend, a number of problems to be solved of 3D display havelong since been pointed out. For example, it is difficult to use anoptimal parallax, which is the cause creating stereoscopic effects. In3D display, the images are, by their nature, not real projections ofthree-dimensional projects but are images dislocated by a certain numberof pixels for the right and left eyes, so that it is not easy to give asense of naturalness to the artificially created stereoscopic effect.

Also, too much parallax can cause problems; in fact, certain viewers of3D images (hereinafter referred to also as “user”) may sometimescomplain of a slight uncomfortable feeling. This, of course, is causedby a variety of factors, which may include not only the 3D displayitself but also a disagreement between the scene being displayed and theuser's surrounding circumstances or sense of reality. However, accordingto our rule of thumb, such a problem tends to occur due to a too largeparallax, that is, when the stereoscopic effect is too strong.

Although what has been described above is matters of human physiology,there are other technical factors that can obstruct the popularizationof contents or applications of stereo images. Stereoscopic vision isrealized by parallax, and suppose that the parallax is represented bythe amount of pixel dislocation between the right and the left image,then there are cases where the same 3D image can be properly viewedstereoscopically or not, due to the differences that exist in hardwarewhich are display apparatuses themselves. If the parallax representingdistant views surpasses the distance between the eyes, it istheoretically impossible to realize stereoscopic vision. Today displayapparatuses, such as PCs (personal computers), television receivers andportable equipment, come in diverse resolutions and screen sizes. And itis difficult, or without methodology to be more accurate, to prepareoptimum contents for 3D display in consideration of such a variety ofhardware.

And even if the methodology is given, it would be difficult to expectthat ordinary programmers will understand it and use it for thepreparation of contents and applications.

The technology disclosed by the above-mentioned literature proposes atechnique that may solve the problems as described above. However, inorder to popularize 3D display in the future, it is necessary to proposeadditional techniques, accumulate new technologies and combine them foruse in products.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoingcircumstances and an object thereof is to propose a new expression for3D display. Another object thereof is to produce or display properstereo images for the user even when there is a change in an image to bedisplayed or a display device. A still another object thereof is toadjust the stereoscopic effect of an on-going 3D display by simpleoperation. Still another object thereof is to lighten the burden on theprogrammer in creating contents or application capable of proper 3Ddisplay. Yet another object thereof is to provide a technology forrealizing proper 3D display as a business model.

The knowledge of inventors that forms a basis for the present inventionis that the appropriate parallax is once separated from hardware of adisplay apparatus or factors such as a distance between a user and thedisplay apparatus (hereinafter, these will be expressed in a unifiedmanner as “hardware”). In other words, the expression of appropriateparallax is generalized by camera interval and optical axis intersectingposition described later, so that it is once described in ageneral-purpose form that is not dependent of hardware. “Not dependentof hardware” means that readout of information inherent in displayapparatus will not be necessary in principle, and if thisgeneral-purpose description is done, it means that a desired 3D displayis realized if parallax images are generated or adjusted based on theappropriate parallax.

By providing a control, in a form of library, that realizes appropriateparallax when acquiring the appropriate parallax and displaying imagesthree-dimensionally, the general programmers can realize, by callingthis library, the appropriate 3D display without being conscious ofcomplicated principles of stereovision or programming.

Among various embodiments of the present invention, the first group isbased on a technique in which appropriate parallax is acquired based onuser's response. This technique is utilized for “initial setting” ofparallax by a user, and if appropriate parallax is once acquired in anapparatus, then the appropriate parallax will be also realized at thetime of displaying other images, thereafter. However, this technique isnot limited to the initial setting but also utilized for “manualadjustment” by which the user adjusts, as appropriate, parallax ofimages during display. The following relates to the first group.

The present invention relates to a three-dimensional image processingapparatus, and it includes: an instruction acquiring unit which acquiresa response of a user to a three-dimensional image displayed on the basisof a plurality of viewpoint images corresponding to differentparallaxes; and a parallax specifying unit which specifies anappropriate parallax on the user based on the acquired response.

The instruction acquiring unit is provided, for instance, as GUI(graphical user interface, similarly hereinafter) and displays whilevarying parallax among the viewpoint images. When the stereoscopiceffect that suits the user's liking is realized, that the preferable 3Dsense was attained accordingly is inputted through operation by a buttonor the like.

The “three-dimensional images” are images displayed with thestereoscopic effect, and their entities are “parallax images” in whichparallax is given to a plurality of images. The parallax images aregenerally a set of a plurality of two-dimensional images. Each of imagesthat constitute the parallax images is a “viewpoint image” havingviewpoints corresponding respectively thereto. That is, a parallax imageis constituted by a plurality of viewpoint images, and displaying themresults in a three-dimensional image displayed. Display of athree-dimensional image is also referred to simply as three-dimensionaldisplay.

The “parallax” is a parameter to produce a stereoscopic effect andvarious definitions therefor are possible. As an example, it can berepresented by a shift amount of pixels that represent the same positionamong the viewpoint images. Hereinafter, the present specificationfollows this definition unless otherwise stated.

The appropriate parallax may be such that a range is specified. In thatcase, the both ends of the range are called “limit parallax”.“Specifying the appropriate parallax” may be done with a maximum valuethat can be permitted as parallax of a nearer-positioned objectdescribed later.

A three-dimensional image processing apparatus according to the presentinvention may further include a parallax control unit which performs aprocessing so that the specified appropriate parallax is also realizedin displaying other images. When the other images are three-dimensionalimages generated from three-dimensional data, the parallax control unitmay determine a plurality of viewpoints from which the three-dimensionalimage is generated according to the appropriate parallax. Morespecifically, it may determine distances among the plurality ofviewpoints and intersecting positions of optical axes formed by anobject from the viewpoints. An example of these processings is done by acamera placement determining unit described later. If these processingsare done in real time, the constantly optimal 3D display will berealized.

The parallax control unit may perform control so that the appropriateparallax is realized on a predetermined basic three-dimensional space tobe displayed. An example of this processing is done by a projectionprocessing unit described later.

The parallax control unit may perform control so that the appropriateparallax is realized on coordinates of an object positioned closest in athree-dimensional space and coordinates of an object positioned farthesttherein. An example of this processing is done by the projection unitdescribed later. An object may be static.

Being “nearer-positioned” means a state where there is given a parallaxin a manner such that stereovision is done in front of a surface(hereinafter referred to as “optical axis intersecting surface” also) atcamera's line of sight placed at the respective plurality of viewpoints,namely, intersecting positions of an optical axis (hereinafter referredto as “optical axis intersecting positions” also). Conversely, being“farther-positioned” means a state where there is given a parallax in amanner such that stereovision is done behind the optical axisintersecting surface. The larger the parallax of a nearer-positionedobject, it is perceived closer to a user whereas the larger the parallaxof a farther-positioned object, it is seen farther from the user. Thatis, the parallax is such that a plus and a minus do not invert around bybetween nearer position and farther position and both the positions aredefined as nonnegative values and the nearer-positioned parallax and thefarther-positioned parallax are both zeroes at the optical axisintersecting surface.

As for a portion having no parallax in an object or space displayed, theoptical axis intersecting surface coincides with a screen surface. Thisis because, for pixels having no parallax given, lines of sight formedfrom both left and right eyes reach just the same position within thescreen surface, that is, they intersect there.

In a case when the other images are a plurality of two-dimensionalimages to which parallax has already been given, the parallax controlunit may determine shift amounts of the plurality of two-dimensionalimages in a horizontal direction according to the appropriate parallax.In this embodiment, the input for 3D display is not produced, with ahigh degree of freedom, from three-dimensional data but is the parallaximage to which parallax has already been given, so that the parallax isfixed. In this case, redrawing or rephotographing processing by changinga camera position and going back to the original three-dimensional spaceor actually-shot real space cannot be done. Thus, the parallax isadjusted by horizontally shifting viewpoints that constitute a parallaximage or pixels contained in them.

If the other images are plane images to which depth information is given(hereinafter this will be referred to as “image with depth information”also), the parallax control unit may adjust its depth according to theappropriate parallax. An example of this processing will be done by atwo-dimensional image generating unit in the third three-dimensionalimage processing apparatus described later.

This three-dimensional image processing apparatus may further include aparallax storage unit which records the appropriate parallax, and theparallax control unit may load the appropriate parallax at apredetermined timing, for instance, when this apparatus is started orwhen a three-dimensional processing function or part thereof possessedby this apparatus is started, and with the thus loaded value as aninitial value the processing may be performed. That is, the “start” maybe done in terms of hardware or software. According to this embodiment,once the user decides on the appropriate parallax, an automaticprocessing for adjusting the stereoscopic effect will thereafter berealized. This is a function which would be so-called an “initialsetting of appropriate parallax”.

Another embodiment of the present invention relates to a method forprocessing three-dimensional images and it includes the steps of:displaying to a user a plurality of three-dimensional images due todifferent parallaxes; and specifying an appropriate parallax for theuser based on a user's response to the displayed three-dimensionalimages.

Still another embodiment of the present invention relates also to amethod for processing three-dimensional images and it includes the stepsof: acquiring an appropriate parallax that depends on a user; and addinga processing to images prior to displaying the images to realize theacquired appropriate parallax. Here, the “acquiring” may be a positivelyspecifying processing or a processing of loading from the parallaxstorage unit or the like.

If each of these steps is implemented as a library function forthree-dimensional display and configuration is such that the libraryfunction can be called up as a function from a plurality of programs, itwill not be necessary for a program to describe the program each time inconsideration of hardware of a three-dimensional display apparatus, thusbeing effective.

The second group of the present invention is based on a technique inwhich the parallax is adjusted based on a user's instruction. Thistechnique can be utilized for “manual adjustment” of parallax by a userand the user can change, as appropriate, the stereoscopic effect of animage during display. However, this technique is not limited to themanual adjustment but also can be utilized even when a certain image isdisplayed and then the above-described appropriate parallax is read inand the parallax of the image is automatically adjusted. What differsfrom the automatic adjustment in the first group is that the automaticadjustment in the second group operates on two-dimensional parallaximages or images with depth information, and in a case where theparallax is changed going back to the three-dimensional data, thetechnique of the first group will be used. The following relates to thesecond group.

An embodiment of the present invention relates to a three-dimensionalimage processing apparatus and it includes: an instruction acquiringunit which acquires a user's instruction for a three-dimensional imagedisplayed from a plurality of viewpoint images; and a parallax controlunit which varies, according to the acquired instruction, a parallaxamount among the plurality of viewpoint images. An example of thisprocessing is shown in FIG. 45 which will be described later, and is atypical example of “manual adjustment”. Convenience will increase if theuser's instruction is provided by a simple GUI such as, for example, abutton operation or the like.

Another embodiment of the present invention relates also to athree-dimensional image processing apparatus, and it includes: aparallax amount detecting unit which detects a first parallax amountcaused when displaying a three-dimensional image from a plurality ofviewpoint images; and a parallax control unit which varies parallaxamounts of the plurality of viewpoint images so that the first parallaxamount falls within a range of a second parallax amount which is auser's permissible parallax amount. This is a typical example of“automatic adjustment”, and the above-described appropriate parallax canbe used as the second parallax amount. An example of this processing isshown in FIG. 46 which will be described later.

The parallax amount detecting unit may detect a maximum value of thefirst parallax amount and the parallax control unit may vary theparallax amounts of the plurality of viewpoint images in a manner suchthat the maximum value does not exceed a maximum value of the secondparallax amount. Accordingly, it is intended that the maximum value ofthe parallax amount, namely, limit parallax, shall be preserved in orderto prevent excessive stereoscopic effect due to too much parallax given.The maximum value mentioned here may be considered as the maximum valuein a nearer-position side.

The parallax amount detecting unit may detect the first parallax amountby computing matching of corresponding points among the plurality ofviewpoint images or may detect the first parallax amount recordedbeforehand in any header of the plurality of viewpoint images. Anexample for these processings is shown in FIG. 47 which will bedescribed later.

The parallax control unit may vary parallax amounts among the pluralityof viewpoint images by shifting synthesis positions of the plurality ofviewpoint images. These are common to FIG. 45 to FIG. 47. The shiftingof synthesis positions is the shifting in the horizontal or verticaldirection in units of pixels or the whole image. If the input is imageswith depth information, the parallax control unit may vary the parallaxamount by adjusting the depth information.

Another embodiment of the present invention relates to a method forprocessing three-dimensional images, and it includes the steps of:acquiring a user's instruction for a three-dimensional image displayedbased on a plurality of viewpoint images; and varying, according to theinstruction, a parallax amount among the plurality of viewpoint images.

Still another embodiment of the present invention relates also to amethod for processing three-dimensional images, and it includes thesteps of: detecting a first parallax amount caused when displaying athree-dimensional image from a plurality of viewpoint images; andvarying parallax amounts of the plurality of viewpoint images so thatthe first parallax amount falls within a range of a second parallaxamount which is a user's permissible parallax amount.

The each step may be implemented as a library function forthree-dimensional display and configuration may be such that the libraryfunction can be called up as a function from a plurality of programs.

The third group is based on a technique in which parallax is correctedbased on the position in an image. This “automatic correction” operatesto alleviate user's sense of discomfort or rejection against 3D displayand can be used in combination with the first group and the second grouptechnique. Generally, pointed out are the technical or physiologicalproblems such as those in which, at the time of three-dimensionaldisplay, as it is closer to edge of an image, a plurality of viewpointimages are likely to be observed as being dislocated or a sense ofdiscomfort is likely to be caused. The third group tries to alleviatethis problem by a processing with which parallax is reduced at part nearthe edge of an image or the parallax is adjusted so that an object movesfrom nearer-position side to farther-position side. The followingrelates to the third group.

An embodiment of the present invention relates to a three-dimensionalimage processing apparatus, and it includes: a parallax control unitwhich corrects parallaxes among a plurality of viewpoint images by whichto display three-dimensional images; and a map storage unit which storesa correction map to be referred to by the parallax control unit at thetime of a correction processing, wherein the correction map is describedin a manner such that the parallaxes are corrected based on positionwithin the viewpoint images. As the correction map, there are parallaxcorrection map, distance-sense correction map and so forth.

The parallax control unit diminishes a parallax at the periphery of, forexample, the plurality of viewpoint images or changes the parallax sothat an object is perceived farther from a user. The parallax controlunit may vary the parallax by selectively performing a processing on anyof the plurality of viewpoints images.

If the plurality of viewpoint images are ones generated fromthree-dimensional data, namely, if the viewpoint images can be generatedby going back to the three-dimensional space, the parallax control unitmay vary the parallax by controlling camera parameters when generatingthe plurality of viewpoint images. The camera parameters include adistance between the right and left cameras, an angle formed between anobject and the cameras, an optical axis intersecting position or thelike. Similarly, if a plurality of viewpoint images are generated fromthree-dimensional data, the parallax control unit may vary the parallaxby distorting three-dimensional space itself in, for example, worldcoordinates when generating the plurality of viewpoint images. 31. If,on the other hand, the plurality of viewpoint images are generated fromimages with depth information, the parallax control unit may vary theparallax by manipulating the depth information.

Another embodiment of the present invention relates to a method forprocessing three-dimensional images, and it includes the steps of:acquiring a plurality of viewpoint images to display three-dimensionalimages; and varying parallax among the acquired plurality of viewpointimages, based on positions in the viewpoint images. The each step may beimplemented as a library function for three-dimensional display andconfiguration may be such that the library function can be called up asa function from a plurality of programs.

The fourth group of the present invention provides, as a softwarelibrary, the first to third groups and their related functions, and itrelates to a technology with which to lighten the programmer's burdenand to promote the popularization of 3D display application. Thefollowing relates to the fourth group.

An embodiment of the present invention relates to a method forprocessing three-dimensional images; information related tothree-dimensional display is retained on a memory and the thus retainedinformation is put to common use among a plurality of differentprograms, and when any of those programs displays a three-dimensionalimage, a state of an image which is to be outputted is determined byreferring to the retained information. An example of the state of animage is how much parallax is given to a parallax image or something ofthis sort.

The “retained information” may include any among the format of an imageto be inputted to a 3D image display apparatus, the display order ofviewpoint images and parallax amounts among the viewpoint images. Inaddition to the sharing of the retained information, a processinginherent in 3D image display may be shared by a plurality of programs.An example of the “a processing inherent in 3D image display” is aprocessing in which to determine the retained information. Anotherexample thereof is a processing, relating to graphical user interface,for determining appropriate parallax, a display processing of a parallaxadjusting screen to support the realization of an appropriate parallaxstate, a processing in which the position of head of a user is detectedand tracked, a processing in which images are displayed to adjust the 3Ddisplay apparatus, and so forth.

Another embodiment of the present invention relates to athree-dimensional image processing apparatus, and it includes: athree-dimensional sense adjusting unit which provides a user withgraphical user interface by which to adjust a stereoscopic effect of athree-dimensional display image; and a parallax control unit whichproduces parallax images in such a form as to follow a limit parallaxturned out as a result of adjustment of stereoscopic effect by the user.

This apparatus may further include an information detecting unit whichacquires information to be referred to in order to achieve theappropriateness of 3D display; and a conversion unit which converts,according to the acquired information, the format of the parallax imagesproduced at the parallax control unit.

The parallax control unit may generate the parallax images while obeyingthe limit parallax by controlling the camera parameters based on thethree-dimensional data, may generate the parallax images by controllingthe depth of images having depth information attached thereto, or maygenerate the parallax images after the shift amount of a plurality oftwo-dimensional images having parallax in the horizontal direction hasbeen decided.

The fifth group of the present invention relates to an application orbusiness model using the above-described three-dimensional processingtechnologies or their related technologies. A software library for thefourth group can be utilized. The following relates to the fifth group.

An embodiment of the present invention relates to a method forprocessing three-dimensional images, and the method is such that anappropriate parallax to display a parallax image three-dimensionally isonce converted to a form of representation which does not depend onhardware of a display apparatus, and the appropriate parallax by thisform of representation is distributed among different displayapparatuses.

Another embodiment of the present invention relates also to a method forprocessing three-dimensional images, and it includes the steps of:reading a user's appropriate parallax acquired by a first displayapparatus into a second display apparatus; adjusting parallax ofparallax images by the second display apparatus according to theappropriate parallax; and outputting from the second display apparatusthe parallax images after adjustment. For example, the first displayapparatus is an apparatus that the user normally utilizes whereas thesecond display apparatus is an apparatus that is provided at a differentplace. It may further include: reading information on the first displayapparatus into the second display apparatus; and correcting, by thesecond display apparatus according to the appropriate parallax, parallaxof the parallax images whose parallax has been adjusted by the step ofadjusting parallax of parallax images, based on the read-in informationon hardware of the first display apparatus and information on hardwareof the second display apparatus.

The information on hardware may include at least any of the size of adisplay screen, an optimum observation distance of a display apparatusand image separability of the display apparatus.

Another embodiment of the present invention relates to athree-dimensional image processing apparatus, and it includes a firstdisplay apparatus, a second display apparatus and a server connected viaa network, wherein the first display apparatus sends user's appropriateparallax information acquired by said three-dimensional image processingapparatus to the server, the server receives the appropriate parallaxinformation and records this in association with a user, and when theuser requests output of image data at the second display apparatus, saidthree-dimensional image processing apparatus reads out appropriateparallax information for the user from the sever, adjusts parallax andthen outputs a parallax image.

The sixth group of the present invention is based on a new techniquethrough which a new expression method using three-dimensional images isproposed.

An embodiment of the present invention relates to a three-dimensionalimage processing apparatus. This three-dimensional image processingapparatus is a three-dimensional image processing apparatus whichdisplays three-dimensional images based on a plurality of viewpointimages corresponding to different parallaxes, and it includes: arecommended parallax acquiring unit which acquires a parallax rangerecommended in the event that the three-dimensional image is displayedby utilizing the three-dimensional image displaying apparatus; and aparallax control unit which sets parallax so that the three-dimensionalimage is displayed within the acquired recommended parallax range.

It may further include: an object specifying unit which receives, from auser, specification of a predetermined object contained in thethree-dimensional image; and an optical axis intersecting positionsetting unit which associates intersecting positions of optical axesassociated with the respective plurality of viewpoint images withspecified object positions and which sets the intersecting positions ofoptical axes so that the specified object is expressed in the vicinityof a position of a display screen on which the three-dimensional imageis displayed.

It may further include a specified information adding unit whichassociates, with the object, optical axis corresponding informationindicating that for the specified object the object is associated withthe intersecting position of the optical axis and the object isexpressed in the vicinity of the position of the display screen.

The optical axis intersecting position setting unit may acquire theoptical axis corresponding information, associate the intersectingposition of the optical axis with the object described in the acquiredoptical corresponding information and the object associated with theintersecting position of axis may be expressed in the vicinity of theposition of the display screen on which the three-dimensional image isdisplayed.

It may further include an identification information acquiring unitwhich acquires identification information, associated with image dataused in generating the three dimensional images, containing informationon whether or not to express within a basic representation spacecontaining an object to be three-dimensionally displayed, wherein theparallax control unit may causes the acquired identification informationto be reflected when the object is expressed in a three-dimensionalimage.

The identification information may contain information on timing atwhich the object is expressed in the basic representation space and whenthe object is expressed in a three-dimensional image, the identificationinformation acquiring unit may reflect the acquired timing.

Another embodiment of the present invention relates to a method forprocessing three-dimensional images. This method for processingthree-dimensional images is such that a predetermined object containedin a three-dimensional image which is displayed based on a plurality ofviewpoint images corresponding to different parallaxes is selectable,and if an object is selected, an optical axis intersection positionassociated with the respective plurality of viewpoint images isassociated to a position of the selected object and the optical axisintersecting position is made to approximately coincide with a positionof a display screen on which the three-dimensional image is to bedisplayed. According to this method for processing three-dimensionalimages, the display screen is set to a boundary between afarther-position space and a nearer-position space, so that anexpression in which an object is in a position toward a viewer beyondthe display screen is possible.

The specified object may have a predetermined boundary face and theoptical axis intersecting position setting unit may associate theintersecting position of optical axis on the boundary face. Thethree-dimensional image may be generated from three-dimensional data. Ifthe three-dimensional image is generated from the three-dimensionaldata, it is easy to add various effects to the three-dimensional image.For example, when expressing an object in such a manner as to go over aboundary face, namely, a display screen, such an effect as to deform thedisplay screen can be added.

Still another embodiment of the present invention relates also to amethod for processing three-dimensional images. The method forprocessing three-dimensional images is such that in the vicinity of adisplay screen where an three-dimensional image generated based on aplurality of viewpoint images corresponding to different parallaxes aboundary face that separates one space from another is set as part ofthe three-dimensional image and the three-dimensional image is expressedwith the boundary face being as boundary of nearer-position space andfarther-position space. The boundary face may be a boundary surfacebetween one material and another material and may be a think plate. Asthe thin plate, there are glass plate and paper and so forth.

Still another embodiment of the present invention relates to a methodfor processing three-dimensional images. This method for processingthree-dimensional images includes the step of changing moving velocityof an object which is contained in a three-dimensional image generatedbased on a plurality of viewpoint images corresponding to differentparallaxes and which is to be expressed in a basic representation spacethat contains an object to be three-dimensionally displayed, innearer-position or farther-position direction.

Still another embodiment of the present invention relates also to amethod for processing three-dimensional images. This method forprocessing three-dimensional images is such that when athree-dimensional image is generated based on a plurality of viewpointimages corresponding to different parallaxes, an object to be expressedwithin a basic representation space that contains an object to bethree-dimensionally displayed is expressed so as to fall within apredetermined parallax range and, simultaneously, at least one offorefront surface and rearmost surface of the basic representation spaceis set to a position where no object exists.

Still another embodiment of the present invention relates also to amethod for processing three-dimensional images. This method forprocessing three-dimensional images may be such that when parallax of anobject to be expressed within a basic representation space that containsan object to be three-dimensionally displayed is calculated in the eventthat a three-dimensional image is generated based on a plurality ofviewpoint images corresponding to different parallaxes, the parallax ofan object is calculated as size that contains an extended area in frontof the object in place of actual size of the object. Moreover, if theobject moves further forward in such a form as to contain the extendedarea in front thereof after the object is positioned in forefrontsurface of the basic representation space, the object may be expressedin such a manner as to move the extended area in front thereof.

Still another embodiment of the present invention relates also to amethod for processing three-dimensional images. This method forprocessing three-dimensional images is such that when parallax of anobject to be expressed within a basic representation space that containsan object to be three-dimensionally displayed is calculated in the eventthat a three-dimensional image is generated based on a plurality ofviewpoint images corresponding to different parallaxes, the parallax ofan object is calculated as size that contains an extended area to therear of the object in place of actual size of the object. Moreover, ifthe object is positioned in rearmost surface of the basic representationspace after the object moves further backward in such a form as tocontain the extended area in front thereof, the object may be expressedin such a manner as to move the extended area in back thereof.

The seventh group of the present invention is based on a new techniqueby which to adjust parallax to be set, according to the state of animage.

An embodiment of the present invention relates to a three-dimensionalimage processing apparatus. This three-dimensional image processingapparatus includes a parallax control unit which controls a ratio of thewidth to the depth of an object expressed within a three-dimensionalimage when the three-dimensional image is generated fromthree-dimensional data so that a parallax formed thereby does not exceeda parallax range properly perceived by human eyes.

Another embodiment of the present invention relates also to athree-dimensional image processing apparatus. This three-dimensionalimage processing apparatus includes a parallax control unit whichcontrols a ratio of the width to the depth of an object expressed withina three-dimensional image when the three-dimensional image is generatedfrom a two-dimensional image to which depth information is given so thata parallax formed thereby does not exceed a parallax properly perceivedby human eyes.

Still another embodiment of the present invention relates also to athree-dimensional image processing apparatus. This three-dimensionalimage processing apparatus includes: an image determining unit whichperforms frequency analysis on a three-dimensional image to be displayedbased on a plurality of viewpoint images corresponding to differentparallaxes; and a parallax control unit which adjusts a parallax amountaccording to an amount of high frequency component determined by thefrequency analysis. If the amount of high frequency component is large,the parallax control unit may adjust the parallax amount by making itlarger.

Still another embodiment of the present invention relates also to athree-dimensional image processing apparatus. This three-dimensionalimage processing apparatus includes: an image determining unit whichdetects movement of a three-dimensional image displayed based on aplurality of viewpoint images corresponding to different parallaxes; anda parallax control unit which adjusts a parallax amount according to anamount of the movement of the three-dimensional image. If the amount ofmovement of a three-dimensional image is small, the parallax controlunit may adjust the parallax amount by making it smaller.

Still another embodiment of the present invention relates also to athree-dimensional image processing apparatus. This three-dimensionalimage processing apparatus is such that if a parameter on cameraplacement set for generating viewpoint images is to be changed in theevent of generating three-dimensional images from three-dimensionaldata, the camera parameter falls within threshold values which areprovided beforehand for a variation of the parameter. According to this,a sense of discomfort felt by a viewer of a three-dimensional image dueto a rapid change in parallax can be reduced.

Still another embodiment of the present invention relates also to athree-dimensional image processing apparatus. This three-dimensionalimage processing apparatus is such that in a case when moving images ofthree-dimensional images are generated from two-dimensional movingimages to which depth information are given, control is performed sothat a variation, caused by progression of the two-dimensional movingimages, in a maximum value or minimum value of depth contained in thedepth information falls within threshold values provided beforehand.According to this apparatus, a sense of discomfort felt by a viewer of athree-dimensional image due to a rapid change in parallax can bereduced.

Still another embodiment of the present invention relates to a methodfor processing three-dimensional images. This method for processingthree-dimensional images is such that appropriate parallax of athree-dimensional image displayed based on a plurality of viewpointimages corresponding to different parallaxes is set for each scene.

Still another embodiment of the present invention relates to a methodfor processing three-dimensional images. This method for processingthree-dimensional images is such that appropriate parallax of athree-dimensional image displayed based on a plurality of viewpointimages corresponding to different parallaxes is set at predeterminedtime intervals.

Another embodiment of the present invention relates to athree-dimensional image processing apparatus. This three-dimensionalimage processing apparatus includes: a camera placement setting unitwhich sets a plurality of virtual camera dispositions to generate aplurality of viewpoint images when original data from which athree-dimensional image is generated are inputted; an object areadetermining unit which determines whether an area in which informationon an object to be displayed does not exist is caused or not inviewpoint images generated corresponding to virtual cameras; and acamera parameter adjusting unit which adjusts, in a case when an area inwhich information on an object to be displayed does not exist is caused,at least one of an angle of view of the virtual camera, a camerainterval and an intersecting position of an optical axis so that thereis no longer any area in which information on an object to be displayeddoes not exist.

It is to be noted that any arbitrary combination of the above-describedstructural components and expressions changed between a method, anapparatus, a system, a recording medium, a computer program and so forthare all effective as and encompassed by the present embodiments.

Moreover, this summary of the invention does not necessarily describeall necessary features so that the invention may also be sub-combinationof these described features.

BRIEF DESCRIPTION OF THE DRAWINGS

The above described objectives, other objectives, features andadvantages are further made clear by the following preferred embodimentsand drawings accompanied thereby.

FIG. 1 shows a positional relationship among a user, a screen and areproduced object to be displayed three-dimensionally.

FIG. 2 shows an example of a shooting system to realize a state of FIG.1.

FIG. 3 shows another example of a shooting system to realize a state ofFIG. 1.

FIG. 4 shows still another example of a shooting system to realize astate of FIG. 1.

FIG. 5 shows a model coordinate system used in a first three-dimensionalimage processing apparatus.

FIG. 6 shows a system of world coordinates used in the firstthree-dimensional image processing apparatus.

FIG. 7 shows a camera coordinate system used in the firstthree-dimensional image processing apparatus.

FIG. 8 shows a view volume used in the first three-dimensional imageprocessing apparatus.

FIG. 9 shows a coordinate system after perspective conversion performedon volume of FIG. 8.

FIG. 10 shows a screen coordinate system used in the firstthree-dimensional image processing apparatus.

FIG. 11 shows a structure of a first three-dimensional image processingapparatus.

FIG. 12 shows a structure of a second three-dimensional image processingapparatus.

FIG. 13 shows a structure of a third three-dimensional image processingapparatus.

FIG. 14( a) and FIG. 14( b) show respectively a left-eye image and aright-eye image displayed by a three-dimensional sense adjusting unit ofa first three-dimensional image processing apparatus.

FIG. 15 shows a plurality of objects, having different parallaxes,displayed by a three-dimensional sense adjusting unit of a firstthree-dimensional image processing apparatus.

FIG. 16 shows an object, whose parallax varies, displayed by athree-dimensional sense adjusting unit of a first three-dimensionalimage processing apparatus.

FIG. 17 shows a relationship among camera angle of view, screen size andparallax.

FIG. 18 shows a positional relationship of a shooting system thatrealizes a state of FIG. 17.

FIG. 19 shows a positional relationship of a shooting system thatrealizes a state of FIG. 17.

FIG. 20 shows camera arrangement when a multiple viewpoint image isgenerated with appropriate parallax.

FIG. 21 shows a parallax correction map used in a distortion processingunit of a first three-dimensional image processing apparatus.

FIG. 22 shows camera's viewpoints when parallax images are generatedaccording to the parallax correction map of FIG. 21.

FIG. 23 shows another camera's viewpoints when parallax images aregenerated according to the parallax correction map of FIG. 21.

FIG. 24 shows a correction map used by a distortion processing unit of afirst three-dimensional image processing apparatus.

FIG. 25 shows camera's viewpoints when parallax images are generatedaccording to the parallax correction map of FIG. 24.

FIG. 26 shows a distance-sense correction map used by a distortionprocessing unit of a first three-dimensional image processing apparatus.

FIG. 27 shows camera's viewpoints when parallax images are generatedaccording to the distance-sense correction map of FIG. 26.

FIG. 28 shows another distance-sense correction map used by a distortionprocessing unit of a first three-dimensional image processing apparatus.

FIG. 29 shows camera's viewpoints when parallax images are generatedaccording to the distance-sense correction map of FIG. 28.

FIG. 30( a), FIG. 30( b), FIG. 30( c), FIG. 30( d), FIG. 30( e) and FIG.30( f) are each a top view of parallax distribution obtained with aresult that a distortion processing unit of a first three-dimensionalimage processing apparatus has performed a processing to athree-dimensional space.

FIG. 31 shows a principle of a processing by a distortion processingunit of a first three-dimensional image processing apparatus.

FIG. 32 shows a processing of FIG. 31 in a concrete manner.

FIG. 33 shows a processing of FIG. 31 in a concrete manner.

FIG. 34 shows a processing of FIG. 31 in a concrete manner.

FIG. 35 shows another example of a processing by a distortion processingunit of a first three-dimensional image processing apparatus.

FIG. 36 shows a processing of FIG. 35 in a concrete manner.

FIG. 37 shows a depth map.

FIG. 38 shows an example of a processing by a distortion processing unitof a third three-dimensional image processing apparatus.

FIG. 39 shows a depth map generated by a processing by a distortionprocessing unit of a third three-dimensional image processing apparatus.

FIG. 40 shows another example of a processing by a distortion processingunit of a third three-dimensional image processing apparatus.

FIG. 41 shows an example of a processing by a two-dimensional imagegenerating unit of a second three-dimensional image processingapparatus.

FIG. 42 shows an example of parallax images.

FIG. 43 shows a parallax image where a synthesis position is shifted bya two-dimensional image generating unit of a second three-dimensionalimage processing apparatus.

FIG. 44 shows a processing by an image edge adjusting unit of a secondthree-dimensional image processing apparatus.

FIG. 45 is a flowchart showing a processing by a secondthree-dimensional image processing apparatus.

FIG. 46 is a flowchart showing another processing by a secondthree-dimensional image processing apparatus.

FIG. 47 is a flowchart showing still another processing by a secondthree-dimensional image processing apparatus.

FIG. 48 shows a plane image with a depth map.

FIG. 49 shows a depth map.

FIG. 50 shows how parallax images are generated, based on a depth map,by a two-dimensional image generating unit of a second three-dimensionalimage processing apparatus.

FIG. 51 shows a depth map corrected by a two-dimensional imagegenerating unit of a second three-dimensional image processingapparatus.

FIG. 52 shows how a three-dimensional image processing apparatusaccording to an embodiment is turned into a library and utilized.

FIG. 53 shows a structure such that a three-dimensional display libraryis incorporated into three-dimensional data software.

FIG. 54 shows how a three-dimensional display library is utilized in anetwork-using-type system.

FIG. 55 shows a state in which an image structured by three-dimensionaldata is displayed on a display screen.

FIG. 56 shows another state in which an image structured bythree-dimensional data is displayed on a display screen.

FIG. 57 shows still another state in which an image structured bythree-dimensional data is displayed on a display screen.

FIG. 58 shows a technique in which a boundary face possessed by anobject to be displayed is made to coincide with a display screen.

FIG. 59 shows another state in which an image is shot in a manner suchthat an optical axis intersecting position of two virtual cameras ismade to coincide with one surface of a tank.

FIG. 60 shows a structure of a fourth three-dimensional image processingapparatus.

FIG. 61 is, for convenience, an illustration of a basic representationspace T concerning an image displayed on a fourth three-dimensionalimage processing apparatus.

FIG. 62 is a drawing in which an area where no object exists isrepresented in such a manner as to be included in a basic representationspace T.

FIG. 63 is a drawing in which an area where no object exists isrepresented in such a manner as to be included in a basic representationspace T.

FIG. 64 shows how a moving object, as an object for parallaxcalculation, is formed in such a manner that not only the bird 330 alonebut also spaces in front and back are included therein.

FIG. 65 shows how a bird is moved in a previously included space after amoving object has gone past a front projection plane.

FIG. 66 shows a state in which a viewer is viewing a three-dimensionalimage on a display screen.

FIG. 67 shows a camera placement determined by a camera placementdetermining unit.

FIG. 68 shows how a viewer is viewing a parallax image obtained with thecamera placement shown in FIG. 67.

FIG. 69 shows how a viewer at a position of the viewer shown in FIG. 66is viewing on a display screen an image whose appropriate parallax hasbeen obtained at the camera placement of FIG. 67.

FIG. 70 shows a state in which a nearest-position point of a spherepositioned at a distance of A from a display screen is shot from acamera placement shown in FIG. 67.

FIG. 71 shows a relationship among two cameras, optical axis tolerancedistance of camera and camera interval required to obtain parallax shownin FIG. 70.

FIG. 72 shows a state in which a farthest-position point of a spherepositioned at a distance of T-A from a display screen is shot from acamera placement shown in FIG. 67.

FIG. 73 shows a relationship among two cameras, optical axis tolerancedistance of camera and camera interval required to obtain parallax shownin FIG. 72.

FIG. 74 shows a relationship among camera parameters necessary forsetting the parallax of a 3D image within an appropriate parallax range.

FIG. 75 shows a relationship among camera parameters necessary forsetting the parallax of a 3D image within an appropriate parallax range.

FIG. 76 shows a structure of a fifth three-dimensional image processingapparatus.

FIG. 77 shows a relationship among a temporary camera position to be setby a producer of three-dimensional data, an angle of view and first tothird objects.

FIG. 78 shows a state in which two virtual cameras are placed based onvirtual camera positions determined in FIG. 77.

FIG. 79 shows a state in which a camera placement is so adjusted thatarea with no object information will not be produced.

FIG. 80 is a flowchart showing a processing for the adjustment of angleof view.

FIG. 81 shows a relationship between a three-dimensional photographyapparatus, which takes stereoscopic photographs in an entertainmentfacility or photo studio, and an object.

FIG. 82 shows a structure of a sixth three-dimensional image processingapparatus.

FIG. 83 is a drawing showing a state in which a camera is remotelyoperated and images being shot are viewed by a three-dimensional displayapparatus.

FIG. 84 shows an example of shooting by a three-dimensional photographyapparatus equipped with a sixth three-dimensional image processingapparatus.

FIG. 85 shows how image separability is measured by an illuminometer.

FIG. 86 shows a moiré image used to measure image separability.

FIG. 87 shows an example of the conversion of appropriate parallax.

FIG. 88 is a drawing showing another example of the conversion ofapproximate parallax.

FIG. 89 is a drawing showing a table to be used in a simplifieddetermination of parallax and basic representation space.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described based on preferred embodiments whichdo not intend to limit the scope of the present invention but exemplifythe invention. All of the features and the combinations thereofdescribed in the embodiments are not necessarily essential to theinvention.

FIG. 1 shows a positional relationship among a user 10, a screen 12 anda reproduced object 14 to be stereoscopically displayed. The eye-to-eyedistance of the user 10 is E, the distance between the user 10 and thescreen 12 is D, and the width of the reproduced object 14 when displayedis W. The reproduced object 14, which is 3D-displayed, has pixels thatlook nearer than the screen 12, namely nearer-positioned pixels, andthose that look farther than the screen 12, namely farther-positionedpixels. The pixels with no parallax given appear to be on the screen 12because they appear to be in the same positions on the screen 12 fromboth eyes.

FIG. 2 shows a shooting system for generating an ideal display ofFIG. 1. The interval between the two cameras 22 and 24 is E, and thedistance from them to the optical axis intersecting position when a realobject 20 is viewed from them (called an optical axis intersectingdistance) is D. And if an object 20 whose width is actually W is shot atan angle of view formed by lines of sight so as to realize the samewidth as the screen 12, a parallax image can be obtained from the twocameras. By displaying this on the screen 12 of FIG. 1, the ideal stateof FIG. 1 can be realized.

FIGS. 3 and 4 show, respectively, the states of A times (A<1) and Btimes (B>1) the positional relationship of FIG. 2. The parallax imagesobtained in these positional relationships can also realize the idealstate of FIG. 1. That is, the basics of ideal 3D display begins withensuring a constant ratio of W:D:E. This relationship serves also as abasis for producing parallax.

FIGS. 5 to 10 show an outline of processing for 3D display based onthree-dimensional data on objects 20 according to an embodiment of thepresent invention.

FIG. 5 is a model coordinate system, namely, a coordinate spacepossessed by individual 3D objects 20. This space provides coordinateswhen a modeling of an object 20 is done. Normally the origin is placedat the center of an object 20.

FIG. 6 shows a system of world coordinates. The world space is a widespace where a scene is formed with objects 20, the floor and the wallsarranged. A process from the modeling of FIG. 5 to the determination ofa world coordinate system as in FIG. 6 can be recognized as a“structuring of three-dimensional data”.

FIG. 7 shows a camera coordinate system. A conversion to a cameracoordinate system is done by positioning a camera 22 at an arbitraryangle of view in an arbitrary direction from an arbitrary position of aworld coordinate system. The position, the direction and the angle ofview are camera parameters. In 3D display, the parameters are decidedfor two cameras, so that the camera interval and the optical axisintersection position are also decided. Since a middle point between thetwo cameras is moved to the origin, origin movement is done also.

FIGS. 8 and 9 show perspective coordinate systems. Firstly, as shown inFIG. 8, a space to be displayed is clipped at a front projection plane30 and a back projection plane 32. As will be described later, one ofthe features of an embodiment is that a plane with a nearer-positionedmaximum parallax point is used as the front projection plane 30 and aplane with a farther-positioned maximum parallax point as the backprojection plane 32. After the clipping, this view volume is convertedinto a rectangular parallelepiped as shown in FIG. 9. The processing inFIGS. 8 and 9 is called a projection processing also.

FIG. 10 shows a screen coordinate system. For three-dimensional display,the respective images from a plurality of cameras are converted intotheir respective coordinates possessed by the screen, thereby generatinga plurality of two-dimensional images, namely, parallax images.

FIGS. 11, 12 and 13 show the structures of three-dimensional imageprocessing apparatuses 100 having different parts from each other.Hereinbelow, for the sake of convenience, these three-dimensional imageprocessing apparatuses 100 are also called the first, the second and thethird three-dimensional image processing apparatus 100, respectively.Though it is possible that these three-dimensional image processingapparatuses 100 are incorporated in one piece in an apparatus, they areshown here as three separate units to avoid complexity of figurerepresentation. The first three-dimensional image processing apparatus100 proves effective when the object and space to be rendered areavailable from the stage of three-dimensional data, so that the maininput thereto is three-dimensional data. The second three-dimensionalimage processing apparatus 100 proves effective for parallax adjustmentof a plurality of two-dimensional images with parallax already given,namely, existing parallax images, so that two-dimensional parallaximages are inputted thereto. The third three-dimensional imageprocessing apparatus 100 realizes appropriate parallax by operating thedepth information of images with depth information, so that the maininput thereto is images with depth information. These three types ofinput are generically written as “original data”.

When the first to the third three-dimensional image processingapparatuses 100 are to be integrated in a single unit, the structure maybe such that an “image type determining unit” is provided as apreprocessing unit for them and after the determination of athree-dimensional data, parallax image or image with depth information,the most appropriate of the first to the third three-dimensional imageprocessing apparatus 100 can be started.

The first three-dimensional image processing apparatus 100 has afunction of “initial setting” and “automatic adjustment” in setting astereoscopic sense for 3D display. If the user specifies the range ofhis/her appropriate parallax for a three-dimensionally displayed image,it will be acquired by the system and from then on otherthree-dimensional images, when they are to be displayed, will bedisplayed after a conversion processing has been done to them beforehandto realize this appropriate parallax. Accordingly, if the user, as arule, goes through one time of setting procedure, using the firstthree-dimensional image processing apparatus 100, then he/she canthenceforth enjoy 3D displays well suited for himself/herself.

The first three-dimensional image processing apparatus 100 also has asubfunction called “parallax correction” by which the parallax at theperiphery of an image is eased artificially. As was described already,the closer to the edges of an image, the more often the dislocations ofa plurality of parallax images will be recognized as “double images”.The main cause of this is parallax barrier or mechanical errors such asthe curvature of the screen of a display apparatus. For the correctionat the periphery of an image, therefore, various methods are used, whichinclude 1) reducing both the nearer-positioned parallax andfarther-positioned parallax, 2) reducing the nearer-positioned parallaxand keeping the farther-positioned parallax unchanged, and 3) shiftingthe nearer-positioned parallax and the further-positioned parallax as awhole toward the farther-positioned parallax. It is to be noted that thethird three-dimensional image processing apparatus 100 also has this“parallax correction” function, but the processing differs because ofthe difference in input data.

The first three-dimensional image processing apparatus 100 includes athree-dimensional sense adjusting unit 112 which adjusts a stereoscopiceffect based on the response from a user to a three-dimensionallydisplayed image, a parallax information storage unit 120 which stores anappropriate parallax specified by the three-dimensional sense adjustingunit 112, a parallax control unit 114 which reads out the appropriateparallax from the parallax information storage unit 120 and generates aparallax image having the appropriate parallax from original data, aninformation acquiring unit 118 which has a function of acquiringhardware information on a display apparatus and also acquiring a systemof 3D display, and a format conversion unit 116 which changes the formatof the parallax image generated by the parallax control unit 114 basedon the information acquired by the information acquiring unit 118. Theoriginal data is simply called three-dimensional data, but, strictlyspeaking, what corresponds to it is object and space data described in aworld coordinate system.

As examples of information acquired by the information acquiring unit118, there are the number of viewpoints for 3D display, the system of astereo display apparatus such as space division or time division,whether shutter glasses are used or not, the arrangement of viewpointimages in the case of a multiple-eye system, whether there is anyarrangement of viewpoint images with inverted parallax among theparallax images, the result of head tracking and so forth.Exceptionally, however, the result of head tracking is inputted directlyto a camera placement determining unit 132 via a route not shown andprocessed there.

In terms of hardware, the above-described structure can be realized by aCPU, a memory and other LSIs of an arbitrary computer, whereas in termsof software, it can be realized by programs which have GUI function,parallax controlling function and other functions or the like, but drawnhere are function blocks that are realized in cooperation with those.Thus, it is understood by those skilled in the art that these functionblocks can be realized in a variety of forms such as hardware only,software only or combination thereof, and the same is true as to thestructure in what follows.

The three-dimensional sense adjusting unit 112 includes an instructionacquiring unit 122 and a parallax specifying unit 124. The instructionacquiring unit 122 acquires a range of appropriate parallax when it isspecified by the user to the image displayed three-dimensionally. Theparallax specifying unit 124 specifies, based on the range, theappropriate parallax when the user uses this display apparatus. Anappropriate parallax is expressed in a form of expression that does notdepend on the hardware of a display apparatus. Stereoscopic visionmatching the physiology of the user can be achieved by realizing theappropriate parallax.

The parallax control unit 114 essentially includes a camera temporaryplacement unit 130 which temporarily sets camera parameters, a cameraplacement determining unit 132 which corrects the camera parameterstemporarily set according to an appropriate parallax, an origin movingunit 134 which performs an origin movement processing to turn the middlepoint of a plurality of cameras into the origin when the cameraparameters are decided, a projection processing unit 138 which performsthe aforementioned projection processing, and a two-dimensional imagegenerating unit 142 which generates parallax images by performing aconversion processing into screen coordinates after the projectionprocessing. Also, as the need arises, a distortion processing unit 136,which performs a space distortion conversion (hereinafter referred tosimply as distortion conversion also) to ease the parallax at theperiphery of an images, is provided between a camera temporary placementunit 130 and a camera placement determining unit 132. The distortionprocessing unit 136 reads out a correction map to be described laterfrom a correction map storage unit 140 and utilizes it.

If it is necessary to adjust a display apparatus for 3D display, a GUI,which is not shown, may be added for that purpose. Using this GUI, aprocessing may be carried out in such a manner that an optimum displayposition is determined by micro-shifting the whole parallax imagedisplay up, down, right or left.

The second three-dimensional image processing apparatus 100 of FIG. 12receives inputs of a plurality of parallax images. They are simplycalled input images also. The second three-dimensional image processingapparatus 100 loads an appropriate parallax having been acquired by thefirst three-dimensional image processing apparatus 100, adjusts theparallax of input images into an appropriate parallax range and outputsit. In that sense, the second three-dimensional image processingapparatus 100 has an “automatic adjustment” function of parallax.However, in addition to that, it has also a “manual adjustment” functionwith which the user, using the GUI function offered, can change theparallax according to his/her instructions when he/she wants to changethe stereoscopic effect while a 3D display is actually going on.

The parallax of parallax images which has already been generated cannotusually be changed, but, by the use of the second three-dimensionalimage processing apparatus 100, the stereoscopic effect can be changedat a sufficiently practicable level by shifting the synthesis positionof viewpoint images constituting the parallax images. The secondthree-dimensional image processing apparatus 100 displays a satisfactorythree-dimensional sense adjusting function even in a situation where theinput data cannot be traced back to three-dimensional data. Thefollowing description will mainly touch on the differences from thefirst three-dimensional image processing apparatus 100.

The three-dimensional sense adjusting unit 112 is utilized for manualadjustment. The instruction acquiring unit 122 realizes a numericalinput, such as “+n” or “−n” on the screen for instance, and the value isspecified by the parallax specifying unit 124 as an amount of change inparallax. There are some ways conceivable for the relationship betweenthe numerical values and the stereoscopic effect to be instructed. Forexample, the arrangement may be such that “+n” is an instruction for astronger stereoscopic effect and “−n” for a weaker stereoscopic effectand that the larger the value of n, the greater the amount of change instereoscopic effect will be. Also, the arrangement may be such that “+n”is an instruction for a general movement of an object in the directionof a nearer position while “−n” is an instruction for a general movementof an object in the direction of a farther position. As another method,the arrangement may be such that the value of n is not specified, andinstead the “+” and “−” buttons only are displayed and the parallaxchanges at each click on either one of these buttons. The secondthree-dimensional image processing apparatus 100 includes a parallaxamount detecting unit 150 and a parallax control unit 152. Where inputimages are a plurality of parallax images, the parallax amount detectingunit 150 checks out a header area of these parallax images and acquirethe amount of parallax described in the number of pixels, especially,the numbers of pixels of the nearer-positioned maximum parallax and thefarther-positioned maximum parallax, if any. If there is no descriptionof the amount of parallax, a matching unit 158 specifies the amount ofparallax by detecting the corresponding points between parallax imagesby the use of a known technique such as block matching. The matchingunit 158 may perform the processing only on an important area such asthe middle part of an image or may focus its detection on the number ofpixels of the nearer-positioned maximum parallax, which is the mostimportant. The amount of parallax thus detected is sent in the form ofthe number of pixels to the parallax control unit 152.

Generally, when three-dimensional images are displayed on the displayscreen of a portable telephone, there may be little difference amongindividuals as to their response to stereoscopic effects and there maybe cases where the user finds it troublesome to have to input anappropriate parallax. With a 3D display equipment used by an unspecifiedlarge number of users, it is possible that the input of an appropriateparallax strikes the users as troublesome instead of convenient. In sucha case, an appropriate parallax range may be determined by themanufacturer of the three-dimensional image display apparatus or by theproducer of the contents to be displayed by the three-dimensional imagedisplay apparatus, or it may be determined by some other technique, suchas following general guidelines. For example, they may reflect theguidelines or standards drawn up by industrial organizations or academicsocieties related to three-dimensional images. As the example thereof,if there is a guideline “The maximum parallax shall be about 20 mm for a15-inch display screen”, then this guideline may be followed, or aprocessing, such as correction, based on the guideline may be carriedout. In this case, the three-dimensional sense adjusting unit 112 willbe unnecessary.

A position shifting unit 160 of the parallax control unit 152 shifts, inthe horizontal direction, the synthesis position of viewpoint imagesconstituting parallax images so that the amount of parallax betweenviewpoint images may become an appropriate parallax. The shifting may beperformed on either of the viewpoint images. The position shifting unit160 has another operation mode and changes an image synthesis positionsimply following instructions when they are given by a user to increaseor decrease the parallax through the three-dimensional sense adjustingunit 112. In other words, the position shifting unit 160 has both theautomatic adjustment function and the manual adjustment function to beoperated by the user for an appropriate parallax.

A parallax write unit 164 writes the amount of parallax, in the numberof pixels, in the header area of any of the plurality of viewpointimages constituting a parallax image, for the aforementioned parallaxamount detecting unit 150 or for another use. An image edge adjustingunit 168 fills up the loss of pixels which has resulted at the edges ofan image due to the shifting by the position shifting unit 160.

The third three-dimensional image processing apparatus 100 of FIG. 13receives inputs of images with depth information. The thirdthree-dimensional image processing apparatus 100 adjusts depth in such away as to realize an appropriate parallax. It has the above-described“parallax correction” function. A distortion processing unit 174 of aparallax control unit 170 carries out a distortion conversion as will bedescribed later, according to a correction map stored in a correctionmap storage unit 176. The depth information and image after thedistortion conversion are inputted to a two-dimensional image generatingunit 178, where a parallax image is generated. Different from thetwo-dimensional image generating unit 142 of the first three-dimensionalimage processing apparatus 100, this two-dimensional image generatingunit 178 gives consideration to an appropriate parallax here. An imagewith depth information is two-dimensional as an image, so that thetwo-dimensional image generating unit 178, which has, within itself, afunction, though not shown, similar to the position shifting unit 160 ofthe second three-dimensional image processing apparatus 100, generatesstereoscopic effects by shifting the pixels in an image in thehorizontal direction according to the depth information. At this time,an appropriate parallax is realized by a processing to be describedlater.

The processing operations and their principles of each component of thethree-dimensional image processing apparatuses 100 whose structures areas described above are as follows.

FIG. 14( a) and FIG. 14( b) show respectively a left-eye image 200 and aright-eye image 202 displayed in the process of specifying anappropriate parallax by a three-dimensional sense adjusting unit 112 ofa first three-dimensional image processing apparatus 100. The imageseach display five black circles, for which the higher the position, thenearer the placement and the greater the parallax is, and the lower theposition, the farther the placement and the greater the parallax is.

FIG. 15 shows schematically a sense of distance perceived by a user 10when these five black circles are displayed. The user 10 is respondingwith “appropriate” for the range of the sense of distance for thesefive, and this response is acquired by an instruction acquiring unit122. In the same Figure, the five black circles with differentparallaxes are displayed all at once or one by one, and the user 10performs inputs indicating whether the parallax is permissible or not.In FIG. 16, on the other hand, the display itself is done in a singleblack circle, whose parallax is changed continuously, and the user 10responds when the parallax reaches a permissible limit in each of thefarther and the nearer placement direction. The response may be madeusing any known technology, which includes ordinary key operation, mouseoperation, voice input and so forth.

Moreover, the determination of parallax may be carried out by a simplermethod. Similarly, the determination of the setting range of basicrepresentation space may be carried out by a simple method, too. FIG. 89shows a table to be used in a simplified determination of parallax andbasic representation space. The setting range of basic representationspace is divided into four ranks of A to D from the setting with more ofnearer-position space to the setting with only farther-position space,and moreover each of the parallaxes is divided into five ranks of 1 to5. Here, the rank of 5A is to be selected, for instance, if the userprefers a strongest stereoscopic effect and desires a most protruding 3Ddisplay. And it is not absolutely necessary that the rank be determinedwhile checking on a 3D display, but the buttons for determining the rankonly may be displayed. There may be a button for checking thestereoscopic effect by the side of them, and pushing it may produce adisplay of an image for checking the stereoscopic effect.

In both cases of FIG. 15 and FIG. 16, the instruction acquiring unit 122can acquire an appropriate parallax as a range, so that the limitparallaxes on the nearer-position side and the farther-position side aredetermined. A nearer-positioned maximum parallax is a parallaxcorresponding to the closeness which the user permits for a pointperceived closest to himself/herself, and a farther-positioned maximumparallax is a parallax corresponding to the distance which the userpermits for a point perceived farthest from himself/herself. Generally,however, the nearer-positioned maximum parallax often needs to be takencare of for user's physiological reasons, and therefore thenearer-positioned maximum parallax only may sometimes be called a limitparallax, hereinafter.

FIG. 17 shows a principle for actually adjusting the parallax of twoviewpoints when an image to be displayed three-dimensionally is takenout of three-dimensional data. Firstly, limit parallaxes as decided bythe user are converted into subtended angles of a temporarily positionedcamera. As shown in the same Figure, the nearer-positioned andfarther-positioned limit parallaxes can be denoted respectively by M andN, which are the numbers of pixels, and since the angle of view θ of thecamera corresponds to the number of horizontal pixels L of a displayscreen, the nearer-positioned maximum subtended angle φ and thefarther-positioned maximum subtended angle φ, which are the subtendedangles in the numbers of limit parallax pixels, can be represented usingθ, M, N and L.tan(φ/2)=M tan(θ/2)/Ltan(φ/2)=N tan(θ/2)/L

Next, these pieces of information are applied to the taking out of atwo-viewpoint image within a three-dimensional space. As shown in FIG.18, a basic representation space T (its depth is also denoted by T.) isfirst determined. Here, the basic representation space T is determinedby placing limitations on the disposition of objects. The distance froma front projection plane 30, which is the front plane of the basicrepresentation space T, to a camera placement plane, namely, a viewpointplane 208, is denoted by S. T and S can be specified by the user. Thereare two viewpoints, and the distance of an optical axis intersectionplane 210 thereof from the viewpoint plane 208 is to be D. The distancebetween the optical axis intersection plane 210 and the front projectionplane 30 is denoted by A.

Then, if the nearer-positioned and the farther-positioned limit parallaxwithin the basic representation space T are denoted by P and Qrespectively, thenE:S=P:AE:S+T=Q:T−Aholds. E is the distance between viewpoints. Now, point G, which is apixel without parallax given, is positioned where the optical axes K2from the both cameras intersect with each other on the optical axisintersection plane 210, and the optical axis intersection plane 210 ispositioned at a screen surface. The beams of light K1 that produce thenearer-positioned maximum parallax P intersect on the front projectionplane 30, and the beams of light K3 that produce the farther-positionedmaximum parallax Q intersect on the back projection plane 32.

P and Q will be expressed by using φ and φ as in FIG. 19:P=2(S+A)tan(φ/2)Q=2(S+A)tan(φ/2)As a result thereof,E=2(S+A)tan(θ/2)•(SM+SN+TN)/(LT)A=STM/(SM+SN+TN)is obtained. Now, since S and T are known, A and E are automaticallydetermined, thus automatically determining the optical axis intersectiondistance D and the distance E between cameras and determining the cameraparameters. If the camera placement determining unit 132 determines thepositions of cameras according to these parameters, then from here on,parallax images with an appropriate parallax can be generated andoutputted by carrying out the processings of the projection processingunit 138 and the two-dimensional image generating unit 142 independentlyfor the images from the respective cameras. As has been described, E andA, which do not contain hardware information, realize a mode ofrepresentation not dependent on hardware.

Subsequently, if the cameras are placed in observance of A or D and Efor 3D display of other images, too, then an appropriate parallax can berealized automatically. All the process from specification of anappropriate parallax to an ideal 3D display can be automated. Thus, ifthis function is offered as a software library, programmers who producecontents or applications need not to be conscious of programming for 3Ddisplay. Also, if L, M and N are represented by the numbers of pixels,then L will be indicative of display range; therefore, it is possible tospecify by L whether the display is to be a display by a whole screen orby part of the screen. L is also a parameter which is not dependent onhardware.

FIG. 20 shows a four-eye camera arrangement by four cameras 22, 24, 26and 28. To be precise, the above-mentioned A and E should be determinedto achieve an appropriate parallax between adjacent cameras, such asbetween the first camera 22 and the second camera 24. However, in asimplified processing, nearly the same effect is obtained by using the Aand E determined between the second camera 24 and the third camera 26,which are closer to the center, as those between the other cameras aswell.

Although T has been said to be a limitation on the disposition ofobjects, T may be decided by a program as a basic size ofthree-dimensional space. In this case, the objects may be arrangedwithin the basic representation space T only throughout the program, or,for an effective display, parallaxes may sometimes be givenintentionally to the objects such that they fly out of the space.

As another example, T may be determined for the coordinates of thenearest-positioned object and the farthest-positioned object in thethree-dimensional space, and if this is done in real time, the objectscan, without fail, be positioned in the basic representation space T. Asan exception to putting objects always in the basic representation spaceT, a short-time exception can be made by applying a relaxing conditionthat “the average position of objects in a certain period of time stayswithin the basic representation space T”. Moreover, the objects thatdefine the basic representation space T may be limited to stationaryobjects, and in this case, dynamic objects can be given such exceptionalbehavior as sticking out from the basic representation space T. As stillanother example, a conversion of contracting a space with objectsalready arranged therein into the size of the width T of basicrepresentation space may be performed, and this may also be combinedwith the aforementioned operation. It is to be noted that a techniquefor intentionally displaying objects such that they appear flying out ofthe basic representation space will be described later.

It is to be noted that if the three-dimensional sense adjusting unit 112of the first three-dimensional image processing apparatus 100 is so setas to have a tendency to generate double images as images displayed forthe user, then the limit parallaxes will be determined on the smallside, with the result that the frequency of the appearance of doubleimages when other images are displayed can be reduced. It is known thatdouble images often occur when the color and brightness contrast betweenan object and the background, and therefore such images as these may beutilized at a stage of specifying limit parallaxes, that is, at the timeof initial setting.

FIG. 21 through FIG. 36 show processings and their principles of adistortion processing unit 136 of a first three-dimensional imageprocessing apparatus 100.

FIG. 21 shows conceptually an example of a correction map stored in thecorrection map storage unit 140 of the first three-dimensional imageprocessing apparatus 100. The entirety, as it is, of this map, whichserves to correct parallaxes directly, corresponds to a parallax image,and the closer to the periphery, the smaller the parallax is. FIG. 22shows changes in parallax that results when a distortion processing unit136 determines camera placement according to the correction map and acamera placement determining unit 132, which has received it, operatescamera parameters. “Normal parallax” is given when the viewing is in thefront direction from the right and left viewpoint positions of the twocameras, whereas “smaller parallax” is given when the viewing is in thedirection deflecting widely from the front. In practice, the cameraplacement determining unit 132 makes the camera interval smaller forpositions closer to the periphery.

FIG. 23 shows another example in which the camera placement determiningunit 132 changes parallax by changing the placement of cameras accordingto the instructions from the distortion processing unit 136. Here, theleft-hand camera only of the two cameras is moved, and as it is movedtoward the periphery of the image, the parallax changes from “normalparallax” to “intermediate parallax” to “smaller parallax”. This methodinvolves lower computation cost than the one in FIG. 22.

FIG. 24 shows another example of a correction map. This map also changesthe parallaxes; the normal parallax is left untouched near the center ofthe image and the parallax in other parallax correction areas is madesmaller gradually. FIG. 25 shows camera placement which the cameraplacement determining unit 132 changes according to the map. Only whenthe camera direction has deflected widely from the front, “smallparallax” is given with the position of the left camera moving closer tothe right camera.

FIG. 26 shows conceptually another example of a correction map. This mapis designed to correct the sense of distance from the viewpoint to theobject, and to realize it, the camera placement determining unit 132adjusts the optical axis intersection distance of two cameras. If theoptical axis intersection distance is made smaller for positions closerto the periphery of an image, then the objects will look relatively setback in the farther-position direction, so that the purpose can beachieved particularly in the sense that the nearer-positioned parallaxis to be made smaller. To make the optical axis intersection distancesmaller, the camera placement determining unit 132 may change thedirection of the optical axes of the cameras, or, in other words, changethe orientation of either one of the cameras. FIG. 27 shows the changein the positions of optical axis intersection or in the optical axisintersection plane 210 when two-dimensional images are generated by themap of FIG. 26. The closer to the periphery of an image, the nearer theoptical axis intersection plane 210 will be to the camera.

FIG. 28 shows another correction map concerning the sense of distance,and FIG. 29 shows how a camera placement determining unit 132, accordingto the map of FIG. 28, changes the optical axis intersection plane 210,following the instructions from the distortion processing unit 136. Inthis example, objects are positioned in normal positions withoutcorrection in the central area of the image, whereas the position ofobjects is corrected in the peripheral area of the image. For thatpurpose, in FIG. 29, the optical axis intersection plane 210 remainsunchanged near the center of the image, and beyond a certain point, theoptical axis intersection plane 210 gets nearer to the cameras. In FIG.29, the operation is done by changing the orientation of the left cameraonly.

FIGS. 30( a) through 30(f) show another distortion conversion by adistortion processing unit 136. Different from the preceding examples,the camera placement is not changed, but the three-dimensional spaceitself is directly distorted by the camera coordinate system. In FIGS.30( a) through 30(f), the rectangular region represents a top view ofthe original space, and the oblique-lined region a top view of the spaceafter conversion. For example, point U in the original space in FIG. 30(a) is shifted to point V after conversion. This means that this pointhas been shifted in the farther-position direction. In FIG. 30( a), thespace is squeezed more in the depth direction as indicated by thearrows, in positions closer to the periphery, and a sense of distancenot too different from a constant sense of distance as indicated bypoint W in the same Figure is given whether in a nearer position or afarther position. As a result thereof, there is a uniform sense ofdistance at the periphery of the image without any object particularlynearer-positioned, which not only solves the problem of double imagesbut also presents an expression better suited for the physiology of theuser.

FIGS. 30( b), 30(c), 30(d) and 30(e) all show the variations ofconversion wherein the sense of distance at the periphery of an image isbrought closer to a constant value. FIG. 30( f) shows an example inwhich all the points are converted in the farther-position direction.

FIG. 31 shows the principle for realizing the conversion of FIG. 30( a).A cuboid space 228 includes space in which projection processings of afirst camera 22 and a second camera 24 are performed. The view volume ofthe first camera 22 is determined by an angle of view, a frontprojection plane 230 and a back projection plane 232 of the camera, andthat of the second camera 24 is determined by an angle of view, a frontprojection plane 234 and a back projection plane 236 of the camera. Adistortion processing unit 136 carries out distortion conversion on thiscuboid space 228. The origin is the center of the cuboid space 228. Fora multiple-eye type, the number of cameras only increases, and the sameprinciple of conversion applies.

FIG. 32 is an example of distortion conversion, which employs reductionconversion in the Z direction. Actually, processing is done forindividual objects in the space. FIG. 33 is a representation likeningthis conversion to a parallax correction map, where the normal parallaxis associated to the Y axis and the larger the absolute value of X, thesmaller the parallax will be. When X=±A, there is no parallax. Since thereduction conversion here is in the Z direction only, the transformmatrix is as follows:

$\begin{matrix}{( {{X\; 1},{Y\; 1},{Z\; 1},1} ) = {( {{X\; 0},{Y\; 0},{Z\; 0},1} )\begin{bmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & {Sz} & 0 \\0 & 0 & 0 & 1\end{bmatrix}}} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack\end{matrix}$

The conversion will be explained using FIG. 34. First consider theregion where X≧0 and Z≧0. When point (X0, Y0, Z0) moves to point (X0,Y0, Z1) as a result of reduction processing, the reduction rate Sz is

$\begin{matrix}{{Sz} = {Z\;{1/Z}\; 0}} \\{= {{CE}/{{CD}.}}}\end{matrix}$The coordinates of C are (X0, Y0, 0) and those of D are (X0, Y0, B).

E is the point of intersection of a straight line and a plane, and ifits coordinates are (X0, Y0, Z2), then Z2 can be obtained as follows:Z=B−X×B/A(Plane)X=X0,Y=Y0(Straight lines)Z2=B−X0×B/A

Hence,

$\begin{matrix}{{Sz} = {{CE}/{CD}}} \\{= {( {B - {X\; 0 \times {B/A}}} )/B}} \\{= {1 - {X\;{0/A}}}}\end{matrix}$

Generally, in relation to X,Sz=1−X/ASimilar calculation for the other regions of X and Z will produce thefollowing results, and the conversion can be verified:Sz=1−X/A, for X≧0Sz=1+X/A, for X<0

FIG. 35 shows another example of distortion conversion. More strictlyspeaking, in consideration of the radial shooting from the cameras,reduction processings in the X-axis and Y-axis directions are alsocombined. Here, conversion is performed using the middle point betweenthe two cameras as representative of the camera position. The transformmatrix is as follows:

$\begin{matrix}{( {{X\; 1},{Y\; 1},{Z\; 1},1} ) = {( {{X\; 0},{Y\; 0},{Z\; 0},1} )\begin{bmatrix}{Sz} & 0 & 0 & 0 \\0 & {Sy} & 0 & 0 \\0 & 0 & {Sz} & 0 \\0 & 0 & 0 & 1\end{bmatrix}}} & \lbrack {{Equation}\mspace{14mu} 2} \rbrack\end{matrix}$

FIG. 36 is for a verification of this conversion. Here, too, consideredis the region where X≧0 and Z≧0. When point (X0, Y0, Z0) moves to point(X1, Y1, Z1) as a result of reduction processing, the reduction ratesSx, Sy and Sz are:

$\begin{matrix}{{Sx} = {( {{X\; 1} - {X\; 2}} )/( {{X\; 0} - {X\; 2}} )}} \\{= {( {{X\; 4} - {X\; 2}} )/( {{X\; 3} - {X\; 2}} )}} \\{{Sy} = {( {{Y\; 1} - {Y\; 2}} )/( {{Y\; 0} - {Y\; 2}} )}} \\{= {( {{Y\; 4} - {Y\; 2}} )/( {{Y\; 3} - {Y\; 2}} )}} \\{{Sz} = {( {{Z\; 1} - {Z\; 2}} )/( {{Z\; 0} - {Z\; 2}} )}} \\{= {( {{Z\; 4} - {Z\; 2}} )/{( {{Z\; 3} - {Z\; 2}} ).}}}\end{matrix}$Since E is the point of intersection of the plane and the straight line,Sx, Sy and Sz can be found the same way as described above.

It is to be noted that when a space after conversion is represented by aset of planes as above, the processing changes at the tangential line tothe planes themselves, which may sometimes cause a sense of discomfort.In that case, the connection may be made with curved surfaces, or thespace may be constituted by curved surfaces only. The calculationchanges simply to one of obtaining the intersection point E of thecurved surface and the straight line.

In the above example, the reduction rate, which is the same on the samestraight line CD, may be weighted. For example, Sx, Sy and Sz may bemultiplied by a weighting function G(L) for the distance L from thecamera.

FIGS. 37 through 40 show the processings, and their principles, by adistortion processing unit 174 of a third three-dimensional imageprocessing apparatus 100.

FIG. 37 shows a depth map of an image with depth information inputted tothe third three-dimensional image processing apparatus 100, and here thedepths come in a range of K1 to K2 in value. Here, the nearer-positioneddepths are denoted by “positive” values, and the farther-positioneddepths by “negative” values.

FIG. 38 shows a relationship between an original range of depth 240 anda post-conversion range of depth 242. The depth approaches a constantvalue as the position nears the periphery of the image. The distortionprocessing unit 174 converts the depth map in such a manner as to followthis correction. The same applies to the case where parallax is given inthe vertical direction. This conversion, which is the reduction in the Zdirection only, can also be expressed by the following equation:

$\begin{matrix}{( {{X\; 0},{Y\; 0},{Gxy},1} ) = {( {X,Y,{Hxy},1} )\begin{bmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & {Sz} & 0 \\0 & 0 & 0 & 1\end{bmatrix}}} & \lbrack {{Equation}\mspace{14mu} 3} \rbrack\end{matrix}$

And Sz, which is divided into cases by the value of X, is:Sz=1−2X/L, for X≧0Sz=1+2X/L, for X<0Through the above conversion, a new depth map having a new factor shownin FIG. 39 will be generated.

FIG. 40 shows a principle of another distortion conversion for a depthmap. Since the space, more strictly speaking, is radially observed fromthe user 10, the reduction processings in the X-axis and Y-axisdirections are also combined. Here, the middle point between the eyes isused as the viewing position. The specific processings are done with thesame formulas as in FIG. 36. Although the original depth map has Zvalues only, the X values and Y values are also stored when thiscalculation is done. The Z values are converted into pixel shift amountsin the X direction or the Y direction, and the X values and the Y valuesmay be stored as offset values in relation to them.

In any case, the depth map converted by the distortion processing unit174 and the original image are inputted to the two-dimensional imagegenerating unit 178, where a synthesis processing of shifting in thehorizontal direction is carried out to produce appropriate parallax. Thedetails will be described later.

FIGS. 41 through 51 show the processings of a position shifting unit 160of a second three-dimensional image processing apparatus 100 and atwo-dimensional image generating unit 178 of a third three-dimensionalimage processing apparatus 100, which can be grasped as its extension.

FIG. 41 shows the principle of shifting the synthesis position of twoparallax images by the position shifting unit 160. As shown in the sameFigure, the position of a right-eye image R coincides with that of aleft-eye image L in the initial condition. However, if the left-eyeimage L is relatively shifted to the right as shown at the top of thesame Figure, then the parallax in nearer positions will increase and theparallax in farther positions will decrease. Conversely, if the left-eyeimage L is relatively shifted to the left as shown at the bottom of thesame Figure, then the parallax in nearer positions will decrease and theparallax in farther positions will increase.

The above is the essence of parallax adjustment by shifting parallaximages. The shifting may be done for one of the images or for both ofthem in mutually opposite directions. Also, from this principle, it isunderstood that this 3D display system can be applied to all the systemsutilizing parallax, whether they are of the type using glasses or not. Asimilar processing can be applied to multi-viewpoint images orparallaxes in the vertical direction also.

FIG. 42 shows a shift processing at the pixel level. A firstquadrilateral 250 and a second quadrilateral 252 are both caught in aleft-eye image 200 and a right-eye image 202. The first quadrilateral250 is given a nearer-positioned parallax, whose parallax amount isexpressed by a positive number as “6 pixels”. In contrast thereto, thesecond quadrilateral 252 is given a farther-positioned parallax, whoseparallax amount is expressed by a negative number as “−6 pixels”. Here,these parallax amounts are denoted by F2 and F1, respectively.

On the other hand, suppose that the appropriate parallax of the user'sdisplay apparatus is found to be J1 to J2. The position shifting unit160 performs a pixel shift of (J2−F2) for both the synthesis startpositions of the two images. FIG. 43 shows the state after the end ofthe shifting. Now, if F1=−6, F2=6, and J1=−5, J2=4, then the synthesisstart positions are both shifted by −2 pixels, namely, in the entirelyfarther-position direction. The final parallax amounts, as shown in FIG.43, are such that E1=−8 and E2=4, so that they are within the limitparallax at least with regard to the nearer-position direction. It isgenerally believed that double images in the nearer-position directioncause a stronger sense of discomfort than those in the farther-positiondirection and objects of shooting are often shot in nearer positions,and therefore it is basically desirable that the parallax in the nearerpositions lie within the limit. Examples of processing are describedbelow.

1. When a nearer-position point is outside the limit parallax and afarther-position point is within the limit parallax, the nearer-positionpoint is shifted to the limit parallax point. However, the processing isstopped when the parallax of the farther-position point reaches thedistance between the eyes.2. When a nearer-position point is outside the limit parallax and afarther-position point is outside the limit parallax, thenearer-position point is shifted to the limit parallax point. However,the processing is stopped when the parallax of the farther-positionpoint reaches the distance between the eyes.3. Processing is not done when both the nearer-position point andfarther-position point are within the limit parallaxes.4. When a nearer-position point is within the limit parallax and afarther-position point is outside the limit parallax, thefarther-position point is shifted to the limit parallax point. However,the processing is stopped when the nearer-position point reaches thelimit parallax point during the processing.

FIG. 44 shows the loss of image edges due to the shifting of synthesispositions. Here, the shift amount of a left-eye image 200 and aright-eye image 202 is one pixel, so that there occurs a lost part 260of 1-pixel width in each of the right-hand edge of the left-eye image200 and the left-hand edge of the right-eye image 202. At this time, theimage edge adjusting unit 168 compensates the horizontal number ofpixels by duplicating the pixel sequence at the image edges as shown inFIG. 44.

As a method other than this, the lost part 260 may be indicated by aspecific color, such as black or white, or may be non-display.Furthermore, a cutting or adding processing may be performed to restorethe size of an initial image. Moreover, it may be so arranged that thesize of an initial image is made larger than the actual display size inadvance so as to prevent the lost part 260 from affecting the display.

FIG. 45 is a flowchart showing the manual adjustment of parallax by asecond three-dimensional image processing apparatus 100. As shown in thesame Figure, right and left images are first prepared manually asparallax images (S10), and they are distributed via a network or otherroutes (S12). They are received by a second three-dimensional imageprocessing apparatus 100 (S14), and, in the case of this Figure, theimages are first synthesized and displayed just as they are withoutshifting (S16). In other words, assumed here is the case where anappropriate parallax has not yet been acquired or the case where aposition shifting unit 160 is not yet operated. Following this, the userinstructs a parallax adjustment to the three-dimensionally displayedparallax image via a three-dimensional sense adjusting unit 112, and theposition shifting unit 160 receives the instruction in a “manual adjustmode” and adjusts the image synthesis position and displays it (S18).Note that S10 and S12 are the procedure 270 of an image creator and thesteps of S14 and thereafter are the procedure 272 of a secondthree-dimensional image processing apparatus 100. Also, although it isnot shown, the shift amount may be recorded in the header and referencethereto may be made from the next time on for synthesis, which may savethe trouble of readjustment.

FIG. 46 is a flowchart showing an automatic adjustment by a secondthree-dimensional image processing apparatus 100. The generation ofright and left images (S30) and the distribution of the images (S32),which are the procedure 270 of the image creator, are the same as inFIG. 45. The reception of the images (S34) in the procedure 272 of thesecond three-dimensional image processing apparatus 100 is notdifferent. Then, parallaxes given in advance between parallax images,especially the maximum parallaxes, are detected by a matching unit 158of a parallax amount detecting unit 150 (S36), and, on the other hand,appropriate parallaxes, especially the limit parallaxes, are acquiredfrom a parallax information storage unit 120 (S38). After this, aposition shifting unit 160 shifts the synthesis position of the imagesso as to satisfy the limit parallaxes by the aforementioned processing(S40), and the image is three-dimensionally displayed after theprocessings by a parallax write unit 164, an image edge adjusting unit168 and a format conversion unit 116 (S42).

FIG. 47 is a flowchart showing still another automatic adjustment by asecond three-dimensional image processing apparatus 100. After thegeneration of left and right images by the procedure 270 of an imagecreator (S50), the maximum parallax at this point is detected (S52) andrecorded in the header of a viewpoint image of any of the parallaximages (S54). This detection may be accomplished by acorresponding-point matching, but when parallax images are createdmanually by a creator, the maximum parallax is naturally known in theediting process, and therefore it may be recorded. Then the image isdistributed (S56).

On the other hand, the receipt of images (S58) in the procedure 272 ofthe second three-dimensional image processing apparatus 100 is the sameas in FIG. 46. Then the above-mentioned maximum parallax is read outfrom the header by a header inspecting unit 156 of a parallax amountdetecting unit 150 (S60). On the other hand, the limit parallaxes areacquired from a parallax information storage unit 120 (S62), and thesubsequent processings S64 and S66 are the same as the processings S40and S42 in FIG. 46, respectively. According to this method, it is notnecessary to calculate the maximum parallax. Also, it is possible torealize an appropriate three-dimensional sense for the whole image.Moreover, since the shift amount can be recorded in the header, there isno possibility of loss of an original image itself. Though not shown, ifthe detected maximum parallax is recorded in the header even in the caseof FIG. 46, a processings can be made, from the next time on, accordingto the procedure of FIG. 47.

It is to be noted that similar processings are possible even in amultiple-eye system, in which similar processings may be applied to theparallax amounts between the respective adjacent viewpoint images. Inactual practice, however, the maximum parallax of the parallaxes betweensuch a plurality of viewpoint images may be taken as the “maximumparallax” among all the viewpoint images and the shift amount of thesynthesis position may be determined.

It has been mentioned that there may be header information in at leastone of the multiple viewpoint images, but when the multiple viewpointimages are synthesized in a single image, the header of the image can beutilized.

Further, there may be cases where already synthesized images aredistributed. In such a case, the images may be separated once by areverse conversion processing and then resynthesized by calculating thesynthesis position shift amount, or a processing may be performed torearrange the pixels to achieve the same result.

FIGS. 48 through 51 show processings for shifting the synthesis positionfor images with depth information. These are done by a two-dimensionalimage generating unit 178 of a third three-dimensional image processingapparatus 100. FIG. 48 and FIG. 49 each show a plane image 204 and depthmap constituting an image with depth information. Here, nearer-positiondepths are denoted by plus, and farther-position depths by minus. Asobjects, there are a first quadrilateral 250, a second quadrilateral 252and a third quadrilateral 254, and the first quadrilateral 250 has adepth of “4”, the second quadrilateral 252 a depth of “2” and the thirdquadrilateral 254 a depth of “−4”. The first quadrilateral 250 is at thenearest-position point, the second quadrilateral 252 at an intermediatenearer-position point and the third quadrilateral 254 at thefarthest-position point.

Based on the original plane image 204, the two-dimensional imagegenerating unit 178 generates an other viewpoint image by firstperforming a processing of shifting the pixels by values of the depthmap. If reference is to be the left-eye image, the original plane image204 will be the left-eye image as it is. As shown in FIG. 50, aright-eye image 202 is produced by shifting the first quadrilateral 250four pixels to the left, the second quadrilateral 252 two pixels to theleft and the third quadrilateral 254 four pixels to the right. An imageedge adjusting unit 168 fills up a lost part 260 of pixel informationcaused by the movement of the objects by the adjacent pixels, which havea parallax of “0” and are considered to be the background.

Following this, the two-dimensional image generating unit 178 calculatesthe depths satisfying appropriate parallaxes. If the range of depth isto be K1 to K2 and the depth value of each pixel is to be Gxy, then thedepth map will take a form of Hxy changed to Gxy in FIG. 37. Also,suppose that the appropriate parallax of the display apparatus in theuser's possession is found to be J1 to J2. In this case, the depth valueG of each pixel in the depth map will be converted as follows to producea new depth value Fxy:Fxy=J1+(Gxy−K1)×(J2−J1)/(K2−K1)

In the above-mentioned example, if K1=−4, K2=4 and J1=−3, J2=2, thedepth map of FIG. 49 will be converted to the depth map of FIG. 51 bythis conversion formula. That is, “4” is converted to “2”, “2” to “1”and “−4” to “−3”, respectively. The intermediate value between K1 and K2are converted into the value between J1 and J2. For example, the secondquadrilateral 252 will be such that when Gxy=2, Fxy=0.75. When Fxy isnot an integer, a rounding off or a processing to make thenearer-position parallax smaller may be carried out.

While the above-described conversion formula is a case of lineartransformation, multiplication by a weighting function F(Gxy) for Gxyand various other nonlinear transformation are also conceivable. Also,from the original plane image 204, left and right images can be newlycreated by shifting the objects in mutually opposite directions. In thecase of a multiple-eye system, a similar processing may be repeated aplural number of times to generate a multiple-viewpoint image.

The above are structures and operations for the three-dimensional imageprocessing apparatus 100 according to embodiments.

Though the three-dimensional processing apparatus 100 has been describedas an apparatus, this may be a combination of hardware and software andit can be structured by software alone. In such a case, convenience willincrease if an arbitrary part of the three-dimensional image processingapparatus 100 is turned into a library so that calling can be made fromvarious programs. A programmer can skip the part of programming whichrequires knowledge of 3D display. For users, trouble of re-setting willbe saved because the operation concerning 3D display, namely, the GUI isof the same kind irrespective of software or contents and thus theinformation set may be shared by the other software.

Moreover, it is proven useful that information, instead of processingsfor 3D display, can be shared between a plurality of programs. Variousprograms can determine the status of image by referring to suchinformation. An example of information that can be shared is informationacquired by the information acquiring unit 118 of the above-describedthree-dimensional image processing apparatus 100. This information maybe stored in a recording unit (not shown), a correction map storage unit140 or the like.

FIGS. 52 to 54 show an example in which an above-describedthree-dimensional image processing apparatus 100 is used as a library.FIG. 52 shows a usage of a three-dimensional display library 300. Thethree-dimensional display library 300 is referred to in the form ofcalling out functions from a plurality of programs, such as program A302, program B 304 and program C 306. Stored in a parameter file 318 arenot only the above-described information but also the user's appropriateparallaxes and so forth. The three-dimensional display library 300 isused by a plurality of apparatuses, such as apparatus A 312, apparatus B314 and apparatus C 316, via API (Application Program Interface) 310.

Conceivable as examples of program A 302 and others are games,three-dimensional applications which are so-called Web3Ds,three-dimensional desktop screens, three-dimensional maps, viewers ofparallax images which are two-dimensional images, and viewers of imageswith depth information and so forth. Some games may naturally differ inthe usage of coordinates, but the three-dimensional display library 300can cope with that.

On the other hand, examples of apparatus A 312 and others are arbitrarythree-dimensional display apparatuses using parallax, which may includethe two- or multiple-eye parallax barrier type, the shutter glasses typeand the polarizing glasses type.

FIG. 53 shows an example in which a three-dimensional display library300 is incorporated into three-dimensional data software 402. Thethree-dimensional data software 402 is comprised of a program body 404,a three-dimensional display library 300 to realize appropriateparallaxes therefor, and a shooting instruction processing unit 406. Theprogram body 404 communicates with the user via a user interface 410.The shooting instruction processing unit 406 performs a virtual camerashooting of a predetermined scene during the operation of the programbody 404 according to instructions from the user. The shot image isrecorded in an image recording apparatus 412. It is also outputted to athree-dimensional display apparatus 408.

Suppose, for instance, that the three-dimensional data software 402 isgame software. In that case, the user can execute the game whileexperiencing an appropriate three-dimensional effect created by thethree-dimensional display library 300 during the game. When the userdesires to record a scene during the game, for instance, when he/she haswon a complete victory in a competing battle game, the user can recordthe scene by giving instructions to the shooting instruction processingunit 406 via the user interface 410. At that time, parallax images,which will produce an appropriate parallax when reproduced later by thethree-dimensional display apparatus 408, are generated by the use of thethree-dimensional display library 300, and they are recorded in anelectronic album or the like of the image recording apparatus 412. It isto be noted that the recording done in parallax images, which aretwo-dimensional images, does not allow the escape of three-dimensionaldata themselves possessed by the program body 404, which can provide asecurity of copyright protection also.

FIG. 54 shows an example in which a three-dimensional data software 402of FIG. 53 is incorporated into a network-using-type system 430.

A game machine 432 is connected to a server 436 and a user terminal 434via a network which is not shown. The game machine 432, which is one fora so-called arcade game, includes a communication unit 442, athree-dimensional data software 402 and a three-dimensional displayapparatus 440 for displaying a game locally. The three-dimensional datasoftware 402 is the one shown in FIG. 53. The parallax images comingfrom the three-dimensional data software 402 and displayed on thethree-dimensional display apparatus 440 are optimally set in advance forthe three-dimensional display apparatus 440. As will be described later,the adjustment of parallax by the three-dimensional data software 402 isused when images are transmitted to the user via the communication unit442. The display apparatus to be used here may suffice if it has afunction of generating three-dimensional images by adjusting theparallax; that is, the display apparatus is not necessarily one capableof three-dimensional display.

The user terminal 434 is comprised of a communication unit 454, a viewerprogram 452 for viewing three-dimensional images and a three-dimensionaldisplay apparatus 450 of arbitrary size and type for displayingthree-dimensional images locally. A three-dimensional image processingapparatus 100 is implemented in the viewer program 452.

The server 436 is comprised of a communication unit 460, an imagestorage unit 462 which records images shot virtually by the userrelative to the game, and a user information storage unit 464 whichrecords personal information, such as the user's appropriate parallax,mail address and other information, in association with the user. Theserver 436, for instance, functions as an official site for a game andrecords moving images or still images of the user's favorite scenes ornotable matches during the game. 3D display is possible either in movingimages or still images.

One example of image shooting in a structure as described above will beperformed as follows. The user operates 3D display on thethree-dimensional display apparatus 450 of the user terminal 434 inadvance, acquires appropriate parallaxes using the function of thethree-dimensional image processing apparatus 100, and notifies them tothe server 436 via the communication unit 454 to have them stored in theuser information storage unit 464. These appropriate parallaxes are setin general-purpose description independent of the hardware of thethree-dimensional display apparatus 450 in the user's possession.

The user plays a game on the game machine 432 at his/her arbitrarytiming. During that time, 3D display is carried out on thethree-dimensional display apparatus 440 with parallaxes initially set ormanually adjusted by the user. If the user requests a recording ofimages during the play or replay of a game, the three-dimensionaldisplay library 300 built in the three-dimensional data software 402 ofthe game machine 432 acquires the user's appropriate parallaxes from theuser information storage unit 464 of the server 436 via the twocommunication units 442 and 460, generates parallax images in accordancewith them, and stores the parallax images for the virtually shot imagesin the image storage unit 462 again via the two communication units 442and 460. If the user downloads this parallax image to the user terminal434 after he/she goes back home, 3D display can be done with desiredthree-dimensional sense. At that time, too, it is possible to manuallyadjust the parallaxes using the three-dimensional image processingapparatus 100 possessed by the viewer program 452.

According to the example of application as described above, theprogramming for the three-dimensional sense, which has primarily had tobe set for each hardware and each user, is consolidated in thethree-dimensional image processing apparatus 100 and thethree-dimensional display library 300, so that a game softwareprogrammer has absolutely no need to care about the complex requirementsfor 3D display. This is not limited to game software, but the same canbe said of any arbitrary software using 3D display, thus eliminatingrestrictions on the development of contents or applications using 3Ddisplay. Thus, this can dramatically accelerate the popularization ofthese.

In particular, with games or other applications which havethree-dimensional CG data in the first place, there have often beencases where the three-dimensional data already there are not put to usein 3D display mainly because it has been conventionally difficult tocode the 3D display accurately. However, the three-dimensional imageprocessing apparatus 100 and the three-dimensional display library 300according to an embodiment can remove such adverse effect and contributeto the enhancement of 3D display applications.

In FIG. 54, the user registers his/her appropriate parallaxes in theserver 436, but the user may use a game machine 432 by bringing an ICcard or the like with the information recorded. And he/she can recordthe scores regarding the game or favorite images on this card.

The present invention has been described based on the embodiments. Theembodiments are only exemplary, and it is understood by those skilled inthe art that there can exist other various modifications to thecombination of each component and process described above and that suchmodifications are encompassed by the scope of the present invention.Such modified examples will be described hereinbelow.

A first three-dimensional image processing apparatus 100 is capable ofhigh-accuracy processing with the input of three-dimensional data.However, the three-dimensional data may be once brought down to imageswith depth information, and parallax images therefor may be generatedusing a third three-dimensional image processing apparatus 100. As thecase may be, such a processing may result in lower calculation cost.Similarly, it is also possible to create a depth map using ahigh-accuracy corresponding-point matching when inputting a plurality ofviewpoint images and, by bringing down to images with depth information,parallax images therefor may be generated using a thirdthree-dimensional image processing apparatus 100.

In the first three-dimensional image processing apparatus 100, a cameratemporary placement unit 130 is constituted as part of thethree-dimensional image processing apparatus 100, but the temporarycamera positioning may be a preprocessing of the three-dimensional imageprocessing apparatus 100. That is because the processing up to thetemporary placement of cameras can be performed irrespective of theappropriate parallaxes. Similarly, it is also possible to place anyarbitrary processing unit constituting the first, the second and thethird three-dimensional image processing apparatus 100 outside of thethree-dimensional image processing apparatus 100, and the high degree offreedom in structuring the three-dimensional image processingapparatuses 100 will be understood by those skilled in the art.

In the embodiments, description has been made of cases where parallaxcontrol is done in the horizontal direction, but similar processings canbe performed in the vertical direction, too.

A unit may be provided that performs an enlargement processing ofcharacter data during the operation of the three-dimensional displaylibrary 300 or the three-dimensional image processing apparatus 100. Forexample, in the case of a parallax image with two horizontal viewpoints,the horizontal resolution of an image visible to the eyes of the userwill become ½. As a result, the readability of characters may drop, andtherefore a processing to extend the characters two times in thehorizontal direction proves effective. Where there is a parallax in thevertical direction, it is also useful to extend the characters in thevertical direction.

During the operation of the three-dimensional display library 300 or thethree-dimensional image processing apparatus 100, a “display duringoperation portion” may be provided where characters or a mark, such as“3D”, is entered in the image being displayed. In that case, the usercan know whether the image allows the adjustment of parallax or not.

Also, a 3D display/normal display switching unit may be provided. Itwill be convenient if this unit is structured such that it contains GUIand, at the click of a designated button by the user, it can switch thedisplay from 3D display to normal two-dimensional display and viceversa.

The information acquiring unit 118 may be such that it does notnecessarily acquire information by user input only but there may beinformation it can acquire automatically by a plug and play or likefunction.

In the embodiment, the method is such that E and A are derived, but themethod may be such that they are fixed and the other parameters arederived and the variables are freely specified.

Another method of expression will be proposed for 3D display. In generalplane image display, there are limitations in terms of reality on theexpression particularly in the depth direction, such as “when an objectpasses through a boundary face”. Also, it is difficult to have a viewerrecognize the presence of a boundary face separating a space fromanother actually at the surface of a window. Therefore, as explainedhereinafter, it will become possible that displaying objectsthree-dimensionally on a three-dimensional image display apparatusenables the viewers to recognize an agreement between an actual entity,such as a screen or a frame, and the boundary face on an objectexpressed within an image, thus giving rise to a new method ofexpression. Generally, a display screen and a frame around it arerecognized visually. Hence, a displaying method using them as a windowcan be conceived, in which case it is necessary to specify anarrangement of the boundary face between spaces or a plate-like objectat this surface. In this case, an optical axis intersecting position Dwill be specified in the positional relationship shown in FIG. 18.

In the positional relationship of a shooting system shown in FIG. 18,the following relations were obtained if the limit parallaxes in nearerand farther positions within a basic representation space T are P and Q,respectively:E:S=P:AE:S+T=Q:T−AAnd when these relations are solved for the nearer-position andfarther-position limit parallaxes, respectively,E=PS/AE=Q(S+T)/(T−A)are obtained. And a three-dimensional image of an appropriate parallaxrange is obtained by selecting a smaller E of these two E's.

FIG. 55 shows a state in which an image structured by three-dimensionaldata is displayed on a display screen 400. In this image, one glasssurface 401 of a tank 410 coincides with the display screen 400, andthat a fish 301 is swimming in the fish tank 410 is being expressed. Ifprocessing is done in such a manner that the far side of the displayscreen 400 is the farther-position space and the near side thereof thenearer-position space, then the fish 301 is normally expressed as if itis swimming in the farther-position space as shown in FIG. 56, and everynow and then, as shown in FIG. 57, the expression can be made such that“the fish 301 appears in the nearer-position space after breakingthrough the display screen 400”. Moreover, the expression can be madesuch that when the fish 301 passes through the display screen 400, forinstance, “water splashes around the display screen 400 and then theboundary face is restored after the passage of the fish 301”. Anotherexample of expression can be made such that “there is no water in thenearer-position space on this side of the display screen and so after awhile of swimming there, the fish 301 is out of breath and goes back tothe farther-position space by breaking through the boundary face, or thedisplay screen 400, again”.

It is to be noted that when an object has passed through an interface,it is not necessary that the boundary face broken by the passage of theobject be recovered, and it is obvious that a variety of expressions canbe made of the interaction between the boundary face and the object,such as the boundary face remaining broken, the object bumping againstthe boundary face without passing therethrough and the boundary facedeforming, or the shock then only transmitting, an electric shock, forinstance, serving as the effect on images, being added. Also, theboundary face may not only be a simple surface but also the placement ofa plate-like object like glass or a thin object like paper. Further, itis not necessary that the boundary face be perfectly coincident with thedisplay screen, but it may be in the neighborhood thereof. In theexpressing effects as described above, it is obvious that planar imagescannot communicate the circumstances fully to the viewer. Especiallywhen the original data from which three-dimensional images are generatedare three-dimensional data, the editing becomes easier for expressingthe effects as mentioned above.

The expression in which the boundary face possessed by an object to bedisplayed is brought into agreement with the display screen can beaccomplished by a technique shown in FIG. 58. That is, a virtual tank410 is placed in a three-dimensional space and two images are generatedfrom two virtual cameras 430 and 440 positioned to the left thereof. Atthis time, the optical axis intersecting position of the two virtualcameras 430 and 440 is brought into agreement with one surface of thetank. And this kind of image can be shot as shown in FIG. 59. Twovirtual cameras 430 and 440 are disposed above an actual tank 410, andthe tank 410 is shot. At that time, the optical axis intersectingposition of the two virtual cameras is brought into agreement with thewater surface.

FIG. 60 shows a structure of a fourth three-dimensional image processingapparatus 100 to realize the above-described processing. Thisthree-dimensional image processing apparatus 100 is of a structure withan object specifying unit 180 added to the three-dimensional senseadjusting unit 112 of the first three-dimensional image processingapparatus 100 shown in FIG. 11. This object specifying unit 180 performsa processing to position the boundary face of an object specified by theuser near or exactly at the display screen. Here the user is assumed tobe a producer of three-dimensional images, and the above-mentionedprocessing is done at the time of producing or editing three-dimensionalimages. It is to be noted that the user may be a viewer, too.

Firstly, a processing procedure will be explained concerning athree-dimensional image processing apparatus 100 shown in FIG. 60. Anobject specifying unit 180 receives specification of an objectcorresponding to the optical axis intersecting plane of two virtualcameras 430 and 440 from the user via a predetermined input device suchas a mouse and informs a parallax control unit 114 of the specifiedobject. The parallax control unit 114, or more specifically a cameraplacement determining unit 132, makes such an adjustment as to have theplace possessed by the object specified by the user coincide with theoptical axis intersecting plane of the two virtual cameras 430 and 440.The operation other than this processing may be the same as that of thethree-dimensional image processing apparatus 100 shown in FIG. 11. Addedto the object determined like this is information indicating that itwill be displayed in the vicinity of the display screen. This will beread out as appropriate at the time of display to determine the opticalaxis intersection distance D, and the distance E between cameras isdetermined by a processing described earlier.

Another expressing technique will be proposed. When there are aplurality of objects to be displayed on the display screen, it is notnecessary that all the objects always fall within the appropriateparallaxes. For effective display, some of the objects may at times bedisplayed outside of the conditions of appropriate parallax, forinstance, for a certain period under certain conditions. As thistechnique, a way of determining a basic representation space for a stillobject has been described earlier, but, in more detail, for each object,information for determining an object to be expressed within a basicrepresentation space containing objects to be displayedthree-dimensionally (hereinafter referred to simply as “identificationinformation” also) may be added. It is to be noted that an object to beexpressed within a basic representation space is also called a“calculation object for basic representation space”. And, based on thisidentification information, a basic representation space may bedetermined as required.

If the identification information is so structured as can be changed asrequired, then it is possible to flexibly set a condition in which theobject itself is to be excluded from appropriate parallax. For example,if the identification information includes a description of timespecification for exclusion from the appropriate parallax conditions, areturn may be made back to the range of appropriate parallaxautomatically after the passage of the specified time.

Described hereunder is a technique whereby some of the objects aretemporarily excluded from the appropriate parallax conditions fordisplay on the display screen as mentioned above. For example, thecamera placement determining unit 132 in the first three-dimensionalimage processing apparatus 100 shown in FIG. 11 makes corrections to thetemporarily set camera parameters according to the appropriateparallaxes, but the function may be further expanded as follows. Thatis, the camera placement determining unit 132 reads the identificationinformation, which is associated to each object, and arranges the cameraparameters in such a manner as to reflect the identificationinformation.

Still another expressing technique will be proposed. If the front planeand the back plane of a basic representation space, namely, the frontprojection plane, which is the nearer-position limit, and the backprojection plane, which is the farther-position limit, are determined bya certain object, it will become impossible to express motion in thespace before and behind the space corresponding to the object. FIG. 61shows, for convenience, an illustration in the depth direction,especially a basic representation space T, concerning an image displayedon a fourth three-dimensional image processing apparatus 100. A frontprojection plane 310 is set on the left of this Figure and a backprojection plane 312 on the right thereof, and the space between thefront projection plane 310 and the back projection plane 312 is thebasic representation space T. Still objects expressed within the rangeof the basic representation space T are a house 350 on the frontprojection plane 310 side and a tree 370 on the back projection plane312 side. Furthermore, a bird 330, which is a moving object, is movingforward in a space above those two still objects. The movement of thebird 330 can be expressed as long as it is moving within the range ofthe basic representation space T. However, after it has reached thefront projection plane 310 or the back projection plane 312, the bird330 becomes an object placed at the front projection plane as the bird330 shown at the left of FIG. 61 or at the back projection plane, thoughnot shown. Thus the bird 330 will be fixed at the maximum parallax andcannot move further forward or backward in real space. If an object canbe so expressed as to be moving even a little, then the sense of realityabout the object can maintained.

As mentioned above, a processing of excluding a moving object from theobjects for a basic representation space T is conceivable. Yet, exceptfor the cases where a certain effect is to be sought as described above,there is a possibility of the user having a sense of discomfort and soit is often desirable that the expression be done within the range ofbasic representation space T.

Therefore, as shown in FIG. 62, a region without the presence of anyobject is included in the basic representation space T. In FIG. 62, aregion without the presence of any object is provided, as part of thebasic representation space T, in the further front of the house 350,which is a still object in front, and thus the bird 330, which is adynamic object, may be able to move in front of the house 350. In FIG.63, a region without the presence of any object is also furtherprovided, as part of the basic representation space T, in the furtherback of the tree 370, which is a stationary object placed in back.Thereby, the bird 330, which is a dynamic object, may, for instance, beso expressed as to have moved from the back, and even when it has movedfurther forward past the front of the house 350, the expressing can bemade with appropriate parallax because the bird 330 is positioned withinthe basic representation space T. Thus the viewer, who is the user, doesnot have a sense of discomfort about the movement.

As shown in FIG. 64, a moving object 390, as an object for parallaxcalculation, is formed, for instance, in such a manner that not only thebird 330 itself but also the spaces in front and back are includedtherein. When the forefront surface of the moving object 390 reaches thefront projection plane 310, the bird 330 only is moved. In that case, byslowing the moving velocity of the bird 330 from the original speed, thetiming can be delayed for the bird 330 to reach the front projectionplane 310 too quickly to make the expressing thereafter impossible.

As shown in FIG. 65, it may be so arranged, for instance, that after themoving object 390 has gone past the front projection plane 310, the bird330 is allowed to move in a previously included space. By this, themaximum parallax is determined by the moving object 390, and the bird330, which nears the maximum parallax gradually, can keep moving forwardin real space. This can be realized by a judgment to enable or disablethe movement depending on the position of the object, or the bird 330.The moving velocity may be set to any of the originally assumed movingvelocity, a fast velocity or a slow velocity; the flexibility given tothe moving velocity makes a variety of expressions possible. Forexample, by changing the moving velocity slower in positions closer tothe end of the moving object 390, the movement forward can be expressedwhile preventing excessively large parallax amount in the forward andthe backward direction.

Moreover, if another object further makes its appearance in front or inback of it, the maximum parallax will now depend on the object. Hence,the bird 330 is returned gradually to the original position within themoving object 390.

Next, a principle of preventing rapid changes in parallax while changingthe maximum parallax will be explained based on the previously shownFIG. 17 and FIG. 18. As described above, the following relations hold:tan(φ/2)=M tan(φ/2)/LE:S=P:AFrom these equations, the parallax amount on the nearer-position side ofan object in a certain camera setting may be expressed as:M=LEA/(2S(A+S)tan(θ/2))Here, if the object moves forward, A becomes larger, S smaller and theparallax amount larger unless the camera setting is changed.

Here, if M becomes M′, S becomes S′ and A becomes A′ with the movementof the object forward, thenM′=LEA′/(2S′(A′+S′)tan(θ/2))M<M′

With E and A′ of the camera settings changed, the conversion is done asin:M″=LE″A″/(2S′(A″+S′)tan(θ/2))And at this time, if the following relationship:M<M″<M′is satisfied, rapid changes in parallax amount can be prevented when anobject moving toward the viewer is displayed three-dimensionally. It isto be noted that only one of E and A′ may be changed. At this time, M″is expressed asM″=LE″A′/(2S′(A′+S′)tan(θ/2))orM″=LEA″/(2S′(A″+S′)tan(θ/2))

To prevent rapid changes in parallax amount for the movement of anobject in the depth direction, the relationship to be satisfied will be:M>M″>M′

Similarly for the parallax amount N on the farther-position side,N=LE(T−A)/(2(T+S)(A+S)tan(θ/2))N′=LE(T−A′)/(2(T+S')(A′+S′)tan(θ/2))N″=LE″(T−A″)/(2(T+S')(A″+S′)tan(θ/2))are obtained. Here, if the relation:N>N″>N′is satisfied, the moving velocity on an actual coordinate system canprevent rapid changes in parallax amount for the movement of an objecttoward the viewer. Also, if the relation:N<N″<N′is satisfied, rapid changes in parallax amount can be prevented for themovement of an object in the depth direction.

Hereinabove, the structure of a three-dimensional image displayapparatus 100, which realizes expressing techniques as shown in FIGS. 61to 65, is explained. This three-dimensional image display apparatus 100can be realized by a three-dimensional image display apparatus 100 shownin FIG. 60. However, a camera placement determining unit 132 is furtherprovided with a function of reading, from original data, information onthe range on which the calculation is to be done in a basicrepresentation space or information on the change of parallax amount foran object, when correcting the temporarily set camera parametersaccording to the appropriate parallax, and reflecting them on cameraparameters. The information may be incorporated into the original datathemselves or may, for instance, be stored in a parallax informationstorage unit 120.

In the embodiment, the processing is such that the parallax of athree-dimensional image is made smaller when an appropriate parallaxprocessing judges that the parallax is in a state of being too large fora correct parallax condition where a sphere can be seen correctly. Atthis time, the sphere is seen in a form crushed in the depth direction,but a sense of discomfort for this kind of display is generally small.People, who are normally familiar with plane images, tend not to have asense of discomfort, most of the time, as long as the parallax isbetween 0 and a correct parallax state.

Conversely, the processing will be such that the parallax is made largerwhen an appropriate parallax processing judges that the parallax of athree-dimensional image is too small for a parallax condition where asphere can be seen correctly. At this time, the sphere is, for instance,seen in a form swelling in the depth direction, and people may have asense of significant discomfort for this kind of display.

A phenomenon that gives a sense of discomfort to people as describedabove is more likely to occur, for example, when 3D displaying astand-alone object. Particularly when objects often seen in real life,such as a building or a vehicle, are to be displayed, a sense ofdiscomfort with visual appearance due to differences in parallax tendsto be more clearly recognized. To reduce the sense of discomfort,correction needs to be added to a processing that increases theparallax.

When three-dimensional images are to be generated from three-dimensionaldata, the parallax can be adjusted with relative ease by changing thecamera placement. With reference to FIGS. 66 through 71, parallaxcorrection procedures will be shown. This parallax correction can bemade using the above-described first to fourth three-dimensional imageprocessing apparatuses 100. Assumed here is the generation ofthree-dimensional images from three-dimensional data by a firstthree-dimensional image processing apparatuses 100 shown in FIG. 11. Itis to be noted that the above-mentioned correction processing can berealized by the fourth and the sixth three-dimensional image processingapparatus 100 to be described later.

FIG. 66 shows a state in which a viewer is viewing a three-dimensionalimage on a display screen 400 of a three-dimensional image displayapparatus 100. The screen size of the display screen 400 is L, thedistance between the display screen 400 and the viewer is d, and thedistance between eyes is e. The nearer-position limit parallax M and thefarther-position limit parallax N have already been obtained beforehandby a three-dimensional sense adjusting unit 112, and appropriateparallaxes are between the nearer-position limit parallax M and thefarther-position limit parallax N. Here, for easier understanding, thenearer-position limit parallax M only is displayed, and the maximumfly-out amount m is determined from this value. The fly-out amount m isthe distance from the display screen 400 to the nearer-position point.It is to be noted that L, M and N are given in units of “pixels”, andunlike such other parameters as d, m and e, they need primarily beadjusted using predetermined conversion formulas. Here, however, theyare represented in the same unit system for easier explanation.

At this time, assume that in order to display a sphere 21 a cameraplacement is determined as shown in FIG. 67 by a camera placementdetermining unit 132 of a parallax control unit 114, with reference tothe nearest-position point and the farthest-position point of the sphere21. The optical axis intersection distance of the two cameras 22 and 24is D, and the interval between the cameras is Ec. However, to make thecomparison of parameters easier, an enlargement/reduction processing ofthe coordinate system is done in a manner such that the subtended widthof the cameras at the optical axis intersection distance coincides withthe screen size L. At this time, suppose, for instance, that theinterval between cameras Ec is equal to the distance e between eyes andthat the optical axis intersection distance D is smaller than theviewing distance d. Then, in this system, as shown in FIG. 68, thesphere 21 looks correctly when the viewer view it from the cameraposition shown in FIG. 67. If an image generated by a shooting systemlike this is viewed as a sphere 21 on the original three-dimensionalimage display apparatus 100, a sphere 21 elongated in the depthdirection for the whole appropriate parallax range is viewed as shown inFIG. 69.

A technique for judging the necessity of correction to athree-dimensional image using this principle will be presented below.FIG. 70 shows a state in which the nearest-position point of a spherepositioned at a distance of A from the display screen 400 is shot from acamera placement shown in FIG. 67. At this time, the maximum parallax Mcorresponding to distance A is determined by the two straight linesconnecting each of the two cameras 22 and 24 with the point positionedat distance A. FIG. 71 shows the camera interval E1 necessary forobtaining the parallax M shown in FIG. 70 when an optical axis tolerancedistance of the cameras from the two cameras 22 and 24 is d. This can besaid to be a conversion in which all the parameters of the shootingsystem other than the camera interval are brought into agreement withthe parameters of the viewing system. In FIG. 70 and FIG. 71, thefollowing relations hold:M:A=Ec:D−AM:A=E1:d−AEc=E1(D−A)/(d−A)E1=Ec(d−A)/(D−A)

And it is judged that a correction to make the parallax smaller isnecessary when E1 is larger than the distance e between eyes. Since itsuffices that E1 is made to equal the distance e between eyes, Ec shallbe corrected as shown in the following equation:Ec=e(D−A)/(d−A)

The same thing can be said of the farthest-position point. If thedistance between the nearest-position point and the farthest-positionpoint of a sphere 21 in FIG. 72 and FIG. 73 is T, which is a basicrepresentation space, thenN:T−A=Ec:D+T−AN:T−A=E2:d+T−AEc=E2(D+T−A)/(d+T−A)E2=Ec(d+T−A)/(D+T−A)

Moreover, it is judged that a correction is necessary when the E2 islarger than the distance e between eyes. Subsequently, since it sufficesthat E2 is made to equal the distance e between eyes, Ec shall becorrected as shown in the following equation:Ec=e(D+T−A)/(d+T−A)

Finally, if the smaller of the two Ec's obtained from thenearest-position point and the farthest-position point, respectively, isselected, there will be no too large parallax for both thenearer-position and the farther-position. The cameras are set byreturning this selected Ec to the coordinate system of the originalthree-dimensional space.

More generally, the camera interval Ec is preferably set in such amanner as to satisfy the following two equations simultaneously:Ec<e(D−A)/(d−A)Ec<e(D+T−A)/(d+T−A)This indicates that in FIG. 74 and FIG. 75 the interval of two camerasplaced on the two optical axes K4 connecting the two cameras 22 and 24placed at the position of viewing distance d at an interval of thedistance e between eyes with the nearest-position point of an object oron the two optical axes K5 connecting the above-mentioned two cameras 22and 24 with the farthest-position point thereof is the upper limit ofthe camera interval Ec. In other words, the two cameras 22 and 24 ispreferably placed in such a manner that they are held between theoptical axes of the narrower of the interval of the two optical axes K4in FIG. 74 and the interval of the two optical axes K5 in FIG. 75.

Although the correction is made here by the camera interval only withoutchanging the optical axis intersection distance, the optical axisintersection distance may be changed and the position of the object maybe changed, or both the camera interval and optical axis intersectiondistance may be changed.

Correction is needed also when a depth map is utilized. If the depth mapvalues denote the dislocation amounts at the points in the number ofpixels and the initial values, or generally the values described in theoriginal data, are in a state realizing an optimum stereoscopic vision,then it is preferably that the above-mentioned processing will not beperformed when there occurs a necessity for enlarging the range of depthmap values by an appropriate parallax processing, and theabove-mentioned processing is performed only when there occurs anecessity for reducing the range of depth map values, that is, whenthere occurs a necessity for making the parallax smaller.

Where the parallax of the initial value is set on the small side, themaximum permissible value may be stored in a header area of the image orthe like and an appropriate parallax processing may be performed suchthat the parallax is set below the maximum permissible value. In thesecases, hardware information is necessary for appropriate distance, but ahigher-performance processing than the previously described one, whichdoes not rely on hardware information, can be realized. Theabove-mentioned processing can be used not only when the parallax isautomatically set but also when it is set manually.

Moreover, the limits of parallax that give a sense of discomfort to theviewers vary with images. Generally speaking, images with less changesin pattern or color and with conspicuous edges tend to cause more crosstalk if the parallax given is large. Images with a large difference inbrightness between both sides of the edges tend to cause a highlyvisible cross talk when parallax given is strong. That is, when there isless of high-frequency components in the images to bethree-dimensionally displayed, namely, parallax images or viewpointimages, the user tends to have a sense of discomfort when he/she seethem. Therefore, it is preferable that images be subjected to afrequency analysis by such technique as Fourier transform, andcorrection be added to the appropriate parallaxes according to thedistribution of frequency components obtained by the analysis. In otherwords, correction that makes the parallax larger than the appropriateparallax is added to the images which have more of high-frequencycomponents.

Moreover, images with less movement tend to cause a highly visible crosstalk. Generally speaking, the type of a file is often identified asmoving pictures or still pictures by checking the extension of afilename. When determined to be moving images, the state of motion maybe detected by a known motion detection technique, such as motion vectormethod, and correction may be added to the appropriate parallax amountaccording to the status. That is, to images with less motion, correctionis added in such a manner that the parallax becomes smaller than theoriginal parallax. On the other hand, to images with much motion, nocorrection is added. Alternatively, to emphasize motion, correction maybe added such that the parallax becomes larger than the originalparallax. It is to be noted that the correction of appropriateparallaxes is only one example, and correction can be made in any caseas long as the parallax is within a predetermined parallax range.Moreover, the depth map may be corrected, and an amount of synthesisposition dislocation of parallax images may be corrected as well.

Moreover, these analysis results may be recorded in the header area of afile, and a three-dimensional image processing apparatus may read theheader and use it for the subsequent display of three-dimensionalimages.

Moreover, the distribution of amount or motion of high-frequencycomponents may be ranked according to actual stereoscopic vision by theproducer or user of images. Or, ranking by stereoscopic vision may bemade by a plurality of evaluators and the average values may be used,and the technique used for the ranking does not matter here.

Moreover, it is not necessary that the appropriate parallaxes bepreserved strictly. And it is not necessary to calculate the cameraparameters at all times, but they may be calculated at fixed timeintervals or at every scene change or in the like manner. It may proveeffective particularly with apparatuses whose processing capacity islow. For example, when the camera parameters are calculated at fixedtime intervals and three-dimensional images are to be generated fromthree-dimensional data, the parallax control unit 114 in the firstthree-dimensional image processing apparatus 100 may instructre-calculation of camera parameters to the camera placement determiningunit 132 at fixed periods using an internal timer. The internal timermay use the reference frequency of CPU, which performs arithmetic of thethree-dimensional image processing apparatus 100, or a timer forexclusive use may be provided separately.

FIG. 76 shows a structure of a fifth three-dimensional image processingapparatus 100 that realizes calculating the appropriate parallaxesaccording to the state of images. Here, an image determining unit 190 isnewly added to the first three-dimensional image processing apparatus100 shown in FIG. 11. Other than that, the structure and operation arethe same, and so the differences will be explained mainly. This imagedetermining unit 190 includes a frequency component detecting unit 192,which acquires the amount of high-frequency components by analyzing thefrequency components of an image and notifies a parallax control unit114 of parallaxes appropriate for the image, and a scene determiningunit 194, which detects scene change, if the original data are movingimages, or detects the movement within an image and notifies theparallax control unit 114 of the camera parameter calculation timing.The detection of scene change may be done by a known technique.

When the original data are moving images, constant processing ofadjusting the appropriate parallax by the amount of high-frequencycomponents of the images will increase the processing load on thefrequency component detecting unit 192. There is concern that the use ofan arithmetic processing unit matching the processing load might raisethe cost of the three-dimensional image processing apparatus 100. Sinceit is not necessary that the appropriate parallax be observed strictlyall the time as mentioned earlier, the processing load of the imagedetermining unit 190 can be reduced by employing an structure whereinthe frequency components of images when the images change greatly, suchas at scene change, are analyzed on the basis of the results ofdetection by the scene determining unit 194.

When a plurality of virtual cameras are placed in a three-dimensionalspace and parallax images corresponding to the respective virtualcameras are to be generated, areas without the presence of objectinformation may sometimes occur within those parallax images.Hereinbelow, the principle of the occurrence of areas without thepresence of object information within parallax images and the techniqueto eliminate it will be explained using an example of generatingthree-dimensional images from three-dimensional data. FIG. 77 shows arelationship between a temporary camera position S (Xs, Ys, Zs) to beset by a producer of three-dimensional data, an angle of view θ, andfirst to third objects 700, 702 and 704.

The temporary camera position S (Xs, Ys, Zs) will serve as the center ofvirtual cameras (hereinafter referred to as center position S of camerasalso) when generating the respective parallax images based on aplurality of virtual cameras. The first object 700 is equal to thebackground. Here, the producer sets the angle of view θ and the centerposition S of cameras in such a manner that the second and third objects702 and 704 are placed within the angle of view θ and at the same timethere is object information present in the angle of view θ by the firstobject 700, which is the background image.

Next, by a predetermined program, the parameters of the two virtualcameras 722 and 724, more specifically the camera positions and theirrespective optical axes, are determined so that a desired parallax maybe obtained as shown in FIG. 78 and further the optical axisintersecting position A (Xa, Ya, Xa), which is reference for thenearer-position and farther-position, may be obtained. At this time,when the angle of view θ is equal to the previously determined value,first and second object zero areas 740 and 742, where there is no objectinformation present as shown in this Figure, will occur in the camerapositions of those two virtual cameras 722 and 724, depending, forinstance, on the size of the first object 700, which is a backgroundimage.

The first object zero area 740 is α, in angle, and the second objectzero area 742 is β, and there is no object information in these angleranges. Accordingly, as shown in FIG. 79, the angle of view θ may beadjusted in such a way as to eliminate these α and β. That is, thelarger of the values of α and β is subtracted from the angle of view θ.At this time, the angle of view θ is reduced from both the left andright sides by the value to be subtracted so as not to change thedirection of optical axis, so that the new angle of view θ1 will bedefined by θ1=θ1−2×α or θ1−2×β. However, since there are cases where αand β cannot be known instantly from the parallax image, the angle ofview θ may be adjusted little by little and, at each adjustment, checkmay be made to see whether there has occurred any region without thepresence of object information within the parallax image. Whether or notthere is any region without the presence of object information may, inpractice, be checked by seeing whether there are any data to be inputtedin the pixels of the display screen. Adjustment may be made not only tocause the presence of object information in all the pixels by theadjustment of the angle of view θ only, but also the camera interval Eor the optical axis intersecting position A may be changed.

FIG. 80 is a flowchart showing a processing for the adjustment of theangle of view. This processing for the adjustment of the angle of viewcan be realized by a first three-dimensional image display apparatus 100shown in FIG. 11. Firstly, when original data, from which athree-dimensional image is generated, are inputted to thethree-dimensional image display apparatus 100, a camera temporaryplacement unit 130 determines a center positions S of cameras (S110).Next, based on the center position S of cameras, a camera placementdetermining unit 132 determines the camera angle of view θ (S112),determines the camera interval E (S114) and determines the optical axisintersecting position A of virtual cameras (S116). Moreover, the cameraplacement determining unit 132 performs a coordinate transformationprocessing to the original data, based on the camera interval E and theoptical axis intersecting position A, (S118) and determines whetherthere is object information present in all the pixels of the displayscreen or not (S120).

Where there are any pixels without object information (N of S120),correction is made to narrow the angle of view θ a little (S122), areturn is made to the processing of S114, and from then on, theprocessings of S114 to S120 are continued until object information ispresent in all the pixels. Nevertheless, where adjustment is to be madeto have object information present in all the pixels by the correctionof the angle of view θ only, the processings to determine the camerainterval E in S114 and the optical axis intersecting position A in S116will be skipped. Where object information is present in all the pixels(Y of S120), the processing for the adjustment of the angle of view iscompleted.

The above embodiment has been explained mainly in regard tothree-dimensional images to be generated from the three-dimensionaldata. The following explanation will concern a technique for expressingthree-dimensional images from actually shot images. The differencebetween the case originating from three-dimensional data and the caseoriginating from actually shot images lies in the absence of the conceptof the depth T of a basic representation space in the case originatingfrom actually shot images. This can be rephrased as the depth range Tcapable of appropriate parallax display.

As shown in FIG. 17 and FIG. 18, there are six kinds of parametersnecessary for camera setting to generate three-dimensional images,namely, the camera interval E, the optical axis intersecting distance A,the angle of view θ, the distance S from the front projection plane 30,which is the front plane of a basic representation space, to the cameraplacement place, namely, the viewpoint plane 208, the distance D of theoptical axis intersection plane 210 from the viewpoint plane 208, andthe depth range T. And the following relations hold between theseparameters:E=2(S+A)tan(/2)·(SM+SN+TN)/(LT)A=STM/(SM+SN+TN)D=S+N

Therefore, by specifying three of the six kinds of parameters, E, A, θ,S, D and T, the rest of the parameters can be calculated. While which ofthe parameters to specify is generally up to free choice, E, A and Dhave been calculated by specifying θ, S and T in the previouslydescribed embodiment. Automatic change of θ or S may change theenlargement ratio, thus there is concern that the expression intended bya programmer or photographer might not be possible. Therefore, it isoften undesirable to determine them automatically. As for T, too, it isdesirable to determine it beforehand because it can also be considered aparameter limiting the expressing range. And with three-dimensionaldata, the trouble of changing any of the parameters is about the same.With actual photography, however, the situation differs. Depending onthe structure of cameras, the cost greatly varies and the operabilityalso changes. It is therefore desirable that the parameters to bespecified be changed according to the usage.

FIG. 81 shows a relationship between a three-dimensional photographyapparatus 510, which is used to take stereoscopic photographs in anentertainment facility or photo studio, and an object 552. Thethree-dimensional photography apparatus 510 is structured such that itincludes a camera 550 and a three-dimensional image processing apparatus100. Here, the photographic environment is fixed. That is, the positionsof the camera 550 and the object 552 are predetermined, and theparameters θ, S and T are determined. In this shooting system, theexample shown in FIG. 18 is replaced by an actual camera 550, and twoparallax images, which serve as reference points for a three-dimensionalimage, can be shot only by this single camera 550, which is providedwith two lenses 522 and 524.

FIG. 82 shows a structure of a sixth three-dimensional image processingapparatus 100 which carries out this processing. This three-dimensionalimage processing apparatus 100 has a camera control unit 151 replacingthe parallax detecting unit 150 in the three-dimensional imageprocessing apparatus 100 shown in FIG. 12. The camera control unit 151includes a lens spacing adjusting unit 153 and an optical axis adjustingunit 155.

The lens spacing adjusting unit 153 adjusts the camera interval E, ormore precisely the lens spacing E, by adjusting the positions of the twolenses 522 and 524. The optical axis adjusting unit 155 adjusts D bychanging the respective optical axis directions of the two lenses 522and 524. For the subject 552, appropriate parallax information of athree-dimensional image display apparatus kept at home or the like isinputted via a portable recording medium such as a memory or card or ameans of communication such as the Internet. An information acquiringunit 118 receives the input of the appropriate parallax and notifies itto a camera control unit 151. Upon receipt of the notification, thecamera control unit 151 calculates E, A and D and adjusts the lenses 522and 524, so that the camera 550 performs a shooting with appropriateparallax. This is accomplished because common processings by thethree-dimensional display apparatus to display the object and thethree-dimensional photography apparatus 510 are achieved by the library.

When it is desired that the object, in display, be positioned on thescreen, it is preferable that D and A be determined and the objectpositioned at D be shot. In this case, the calculation of appropriateparallax may be done separately for the nearer-position and thefarther-position, and one which makes E smaller may be selected. T maybe made larger than the range occupied by the object. When there is abackground, T shall be determined such that the background is includedtherein.

Moreover, it is not necessary that the appropriate parallax informationbe that checked by the three-dimensional image display apparatuspossessed by the user, who is the object. For example, a favoritethree-dimensional sense may be selected by a typical three-dimensionalimage display apparatus present at the site of shooting. This selectioncan be made by a three-dimensional sense adjusting unit 112. Orselection may simply be made from the items, such as “On-screen/Fartherposition/Nearer position” or “Three-dimensional sense:Large/Intermediate/Small”, and predetermined camera parameters stored incorrespondence thereto in the parallax information storage unit 120 maybe used. Also, change of the optical axis intersecting position may bemade by a mechanical structure, but it may also be realized by changingthe range used as an image by using a high-definition CCD (ChargeCoupled Device). For this processing, functions of the position shiftingunit 160 may be used.

FIG. 83 shows a state in which a movable camera 550 is placed in a placewhere humans cannot enter, the camera 550 is remotely operated by aremote operation using a controller 519 and images being shot areobserved by a three-dimensional display apparatus 511. Thethree-dimensional display apparatus 100 structured in FIG. 82 isincorporated into the three-dimensional display apparatus 511.

The camera has a mechanism in which the lens interval E can beautomatically adjusted. This camera also has an optical zoom orelectronic zoom function by which to determine θ. However, this zoomingoperation changes a parallax amount. In general, the farther theshooting takes place the angle formed by optical axes among viewpointsat the time of display becomes smaller, so that the parallax becomessmall with the lens interval E and the stereographic effect thereof ispoor. Thus, the camera setting such as lens interval E and zoomingamount needs be properly changed. Here, in such a case as this, thecamera setting is automatically controlled so as to considerably reducethe cumbersome setting for camera. It is noted that the camera settingmay be adjusted by using the controller 519.

An operator first operates the optical zoom or electronic zoom using thecontroller 519 so as to determine θ. Next, the camera 550 is moved so asto display an object desired to be shot in the center of thethree-dimensional display apparatus 511. The camera 550 focuses on anobject by an auto-focus mechanism and, at the same time, acquires adistance. In the initial state, suppose that this distance is D. Inother words, the camera 550 is so set automatically that the object isseen in a position in the vicinity of a display screen. The range of Tcan be manually changed, and the operator specifies the distribution ofan object, whose rear-or-front positional relationship is desired to begrasped beforehand, in the depth direction. In this manner, θ, D and Tare determined. Thereby, E, A and S are determined by theabove-indicated three relational expressions, so that the camera 550 isproperly auto-adjusted. In the case of this example, S is determinedlater. Thus, the range of T is uncertain until the final stage. For thisreason, T may be set larger to some extent.

If the object is desired to be displayed in the edge of a screen, theobject may be once displayed in the center and a predetermined buttonmay be depressed so as to be able to fix the focal point and D and,thereafter, the direction of the camera 550 may be changed. If astructure is such that the focal point or D can be manually changed, thedepth position of an object can be freely changed.

FIG. 84 shows an example of shooting by a three-dimensional photographyapparatus 510. The three-dimensional photography apparatus 510 has thestructure shown in FIG. 82. In this camera 550, the appropriate parallaxof a three-dimensional display apparatus held beforehand by aphotographer is inputted through a recording medium such as a portablememory or a means of communication such as the Internet. Assumed as thecamera 550 here is a camera that has a simple structure and is availableat comparatively low price. Here, camera interval E, optical axisintersection distance D and angle of view θ are fixed and A, S and T aredetermined by the above-indicated three relational expressions. Sincethe appropriate range of distances to the object can be calculated fromthese values, the distance to the object can be measured in real timeand whether or the calculated distance is appropriate or not can benotified to the photographer via message, color of lamp or the like. Thedistance to the object may be acquired using the known techniques suchas a distance measuring function by auto-focusing.

As described above, the combination as to which camera parameter is tobe variable(s) or constants(s) is freely chosen, so that there arevarious modes in accordance with the usage. The mode, for the camera550, conceivable other than the above-described includes a mode wherethe camera is attached to a microscope, a medical endoscope, a portableterminal or various equipment.

There are cases where, if the parallax is optimized for a particularthree-dimensional display apparatus, stereovision may be difficult withother 3D display apparatuses. However, the apparatus' performancegenerally is to improve and it is considered to be a rare case that theparallax is too large for a 3D display apparatus purchased next time.Rather, making the adjustment as above is important to prevent a risk inwhich the stereovision becomes difficult, irrespective of the capabilityof the 3D display apparatus, due to lack of proper setting. It isassumed here that the 3D display apparatus is structured such that athree-dimensional image processing apparatus is provided therein torealize the stereovision.

The appropriate parallax obtained by the three-dimensional senseadjusting unit of the first to the sixth three-dimensional imageprocessing apparatus 100 is the parameters, for a particularthree-dimensional image processing apparatus 100, determined while theuser is viewing three-dimensionally, so that the appropriate parallax ispreserved, from then on, in that three-dimensional processing apparatus100. Two factors, which are “image separability” inherent in the 3Ddisplay apparatus and “physiological limit” inherent in a viewer, areadded to this operation of three-dimensional sense adjustment. The“image separability” is an objective factor that represents thecapability to separate a plurality of viewpoint images. And the crosstalk tends to be easily perceived in the 3D display apparatus, wherethis capability is low, even if almost no parallax is given, and if anumber of viewers make adjustment, the range of the appropriate parallaxbecomes narrow averagely. Conversely, if the image separability is high,the cross talk is hardly perceived even with large parallax given, andthe range of the appropriate parallax becomes wide averagely. The“physiological limit”, on the other hand, is a subjective factor. Forexample, if the image separability is very high and the image iscompletely separated, the parallax range in which no sense of discomfortis felt differs depending on viewers. This appears as a variation in theappropriate parallax in the same three-dimensional processing apparatus100.

The image separability is also called the degree of separation and itcan be determined by a method in which the illuminance of a referenceimage 572 is measured while an illuminometer 570 moves in the horizontaldirection as shown in FIG. 85. At that time, in the case of a two-eyetype, all is displayed white on the left-eye image whereas all isdisplayed black on the right-eye image, for example. If an image iscompletely separated, the illuminance at a place that right eye sees is0. In contrast thereto, the image separability can be obtained bymeasuring the degree of leakage of the white in the left-eye image. Agraph at the far right of this Figure is an example of the measurementresult. Since this measurement is almost equivalent to measuring theshading of moiré, the image separability can be measured if a moiréimage is imported at a distance, where the moiré is viewed as in FIG.86, and its contrasting density is analyzed.

In the spectacle-type three-dimensional apparatus and the like, theimage separability can be measured by measuring the leaked light. Inpractice, the calculation may also be done in a manner such that themeasured value, obtained when both left and right images are all inblack, is taken into account as background. The image separability canbe determined by an average value of ranking evaluation done by a numberof viewers.

In this manner, criteria such as objective values can be set for theimage the image separability of a 3D display apparatus. Hence, forexample, if the rank of a 3D display apparatus 450 of FIG. 54 owned by auser and the user's appropriate parallax for the 3D display 450 arefound, then the appropriate parallax can be converted to suit the rankof a different 3D display apparatus 440. In the 3D display apparatus,there are parameters, serving as characteristic values, such as screensize, pixel pitch and optimum observation distance. And the parameterinformation such as these is utilized for the conversion of theappropriate parallax.

Hereinbelow, examples of the conversion of appropriate parallax will beexplained, in order, for each parameter. Using FIG. 87 and FIG. 88. Itis assumed here that the appropriate parallax is retained in N/L and M/Lwhere M is nearer-position limit parallax, N is farther-position limitparallax and L is the screen size. By expressing in ratio values in thismanner, the difference in the pixel pitch between 3D apparatuses can beignored. Thus, for the sake of simplicity, explanation will be made onthe assumption that the pixel pitch is equal in the Figures used in thefollowing.

Firstly, the conversion to be done when the screen sizes differ will beexplained. It is preferable that a processing be performed in suchmanner that the absolute value of parallax remains the sameirrespectively of the screen size, as shown in FIG. 87. In other words,the range of stereoscopic expression is made identical in the front andback direction. Suppose that the screen size becomes a times as in astate shown in the lower side of the Figure from the upper side of theFigure. Then, N/L is converted to N/(aL) whereas M/L is converted toM/(aL), so that appropriate parallax is realized even when the screensizes differ. This Figure shows an example of the nearest position.

Next, the conversion to be done when the observation distances differwill be explained. As shown in FIG. 88, it is preferable that if theoptimum observation distance d becomes b times, the absolute value ofparallax shall also become b times. That is, the angle formed with eyesis kept constant. Thus, N/L is converted to bN/L and M/L is converted tobM/L, so that the optimum parallax is realized even when the optimumobservation distances differ. This Figure shows an example of thenearest position.

Finally, explanation will be made as to taking into account the factorof image separability. Here, a rank r of image separability is assumedto be an integer greater than or equal to 0 and if the separability isso bad that no parallax can be given, then it will be 0. And let theimage separability of a first 3D display be r0 and let the imageseparability of a second 3D display apparatus be r1, then N/L isconverted to cN/l and M/L is converted to cM/L with c=r1/r0. Thereby,appropriate parallax is realized even if the 3D display apparatuses havedifferent image separabilities. It is noted that the equation used hereto derive c is a mere example and other equations may be used to derivec.

When all of the above procedures are done, N/L is converted to bcN/(aL)and M/L is converted to bcM/(aL) eventually. It is to be noted that thisconversion can be applied to parallax either in the horizontal directionor the vertical direction. The above conversion for optimum parallax canbe realized in the structures shown in FIG. 52, FIG. 53 and FIG. 54.

Moreover, the front face and the back face of the basic representationspace may be determined using a Z buffer. In the Z buffer, a depth mapof objects seen from a camera is obtained using a hidden-surfaceprocessing. The minimum value and the maximum value by which to removethis Z value may be used as positions of forefront surface and farthestback face. As a processing, a processing to acquire a Z value from avirtual camera position will be added. Since the final resolution is notrequired in this processing, the processing time will be reduced if thenumber of pixels is reduced. With this technique, the hidden part isignored, so that the range of appropriate parallax can be effectivelyutilized. Even in a case where there are a plurality of objects, it willbe easily handled.

Moreover, the parallax control unit 114 may perform control in such amanner that if parameters, on camera placement, to be set to generateparallax images are changed in the event of generating three-dimensionalimages by three-dimensional data, the camera parameters fall withinthreshold values provided beforehand for the variation of theparameters. Moreover, in a case when moving images of three-dimensionalimages are generated from two-dimensional moving images to which depthinformation are given, the parallax control unit 114 may perform controlso that a variation, caused by progression of the two-dimensional movingimages, in a maximum value or minimum value of depth contained in thedepth information falls within threshold values provided beforehand.Those threshold values used in the control may be stored in the parallaxinformation storage unit 120.

There are cases where when a basic representation space is determinedfrom objects existing within the angle of view in the event ofgenerating three-dimensional images from three-dimensional data, thesize of the basic representation space changes drastically due to arapid movement of an object or frame-in and frame-out and therefore theparameters on the camera placement change greatly. If this variation islarger than the predetermined threshold value, the variation may bepermitted with the threshold values as the limit. When thethree-dimensional image is to be generated from the two-dimensionalimage to which the depth information is given, the similar inconveniencemay be conceivable in the course of determining the maximum value orminimum value of a parallax amount from the maximum value or minimumvalue of depth. Threshold values may be proved for this variation, too.

According to the embodiments, there are the following effects:

1. The three-dimensional images which are likely to be suited to thehuman physiology can be generated or displayed.

2. Even if an image to be displayed is changed, a three-dimensionalimage suitable for a user can be generated or displayed.

3. The stereoscopic effect for 3D display can be adjusted by a simpleoperation.

4. The burden on the programmer can be lightened in creating contents orapplication capable of proper 3D display.

5. The trouble of a user who tries to optimize can be alleviated.

6. The adjustment of a stereoscopic effect or head tracking informationwhich is not normally considered for an object for plug-and-playfunction can be easily realized, and the same thing is applied to anapparatus where the plug-and-play cannot be done in principle, such asin a case of parallax barrier to be attached later.

As has been described above, the present embodiments can be utilized formethod and apparatus for processing three-dimensional images, and soforth.

Although the present invention has been described by way of exemplaryembodiments, it should be understood that many changes and substitutionsmay further be made by those skilled in the art without departing fromthe scope of the present invention which is defined by the appendedclaims.

1. A three-dimensional image displaying apparatus for displaying athree-dimensional image perceived by one or more users based ontwo-dimensional viewpoint images corresponding respectively to right andleft eyes of the one or more users, the apparatus comprising: a storageunit having pre-stored front and back boundary positions of athree-dimensional object perceived by the user, the front boundaryposition being a limit up to where the three-dimensional object appearsto be maximally close to the user and the back boundary position being alimit up to where the three-dimensional object appears to be maximallydistant from the user; a receiving unit configured to receive a userinstruction selecting front and back boundary positions from thepre-stored front and back boundary positions; and a control unitconfigured to: receive a single two-dimensional image having informationfor generating the two-dimensional viewpoint images from the receivedsingle two-dimensional image; generate the two-dimensional viewpointimages from the received single two-dimensional image based on thereceived information; and adjust parallax between or among thetwo-dimensional viewpoint images based on a parallax amountcorresponding to the user instruction before the three-dimensional imageis displayed so that the three-dimensional object to be perceived by theuser appears between the front and back boundary positions selected bythe user instruction.
 2. The apparatus according to claim 1, wherein theparallax amount is stored in a recording area, and the control unitadjusts the parallax between or among the two-dimensional viewpointimages based on the parallax amount in the recording area.
 3. Athree-dimensional image processing apparatus for processing athree-dimensional image perceived by one or more users based ontwo-dimensional viewpoint images corresponding respectively to right andleft eyes of the one or more users, the apparatus comprising: a storageunit having pre-stored front and back boundary positions of athree-dimensional object perceived by the user, the front boundaryposition being a limit up to where the three-dimensional object appearsto be maximally close to the user and the back boundary position being alimit up to where the three-dimensional object appears to be maximallydistant from the user; a receiving unit configured to receive a userinstruction selecting front and back boundary positions from thepre-stored front and back boundary positions; and a control unitconfigured to: receive a single two-dimensional image having informationfor generating the two-dimensional viewpoint images from the receivedsingle two-dimensional image; generate the two-dimensional viewpointimages from the received single two-dimensional image based on thereceived information; and adjust parallax between or among thetwo-dimensional viewpoint images based on a parallax amountcorresponding to the user instruction before the three-dimensional imageis displayed so that the three-dimensional object to be perceived by theuser appears between the front and back boundary positions selected bythe user instruction.
 4. The apparatus according to claim 3, wherein theparallax amount is stored in a recording area, and the control unitadjusts the parallax between or among the two dimensional viewpointimages based on the parallax amount in the recording area.
 5. Athree-dimensional image processing method for displaying athree-dimensional image perceived by one or more users based ontwo-dimensional viewpoint images corresponding respectively to right andleft eyes of the one or more users, the method comprising the steps of:receiving a user instruction selecting front and back boundary positionsfrom pre-stored front and back boundary positions of a three-dimensionalobject perceived by the user, the front boundary position being a limitup to where the three-dimensional object appears to be maximally closeto the user and the back boundary position being a limit up to where thethree-dimensional object appears to be maximally distant from the user;and receiving a single two-dimensional image having information forgenerating the two-dimensional viewpoint images from the received singletwo-dimensional image; generating the two-dimensional viewpoint imagesfrom the received single two-dimensional image based on the receivedinformation; and adjusting parallax between or among the two-dimensionalviewpoint images based on a parallax amount corresponding to the userinstruction before the three-dimensional image is displayed so that thethree-dimensional object to be perceived by the user appears between thefront and back boundary positions selected by the user instruction. 6.The method according to claim 5, wherein the parallax amount is storedin a recording area, and the adjusting step adjusts the parallax betweenor among the two-dimensional viewpoint images based on the parallaxamount in the recording area.
 7. The three-dimensional image processingmethod according to claim 5, wherein the steps are implemented aslibrary functions for use in a three-dimensional display, and thelibrary functions are called as functions of a plurality of programs. 8.A non-transitory tangible computer-readable medium having a program fordisplaying a three-dimensional image perceived by one or more usersbased on two-dimensional viewpoint images corresponding respectively toright and left eyes of the one or more users, the program, whenexecuted, controlling a computer to perform the steps of: receiving auser instruction selecting front and back boundary positions frompre-stored front and back boundary positions of a three-dimensionalobject perceived by the user, the front boundary position being a limitup to where the three-dimensional object appears to be maximally closeto the user and the back boundary position being a limit up to where thethree-dimensional object appears to be maximally distant from the user;and receiving a single two-dimensional image having information forgenerating the two-dimensional viewpoint images from the received singletwo-dimensional image; generating the two-dimensional viewpoint imagesfrom the received single two-dimensional image based on the receivedinformation; and adjusting parallax between or among the two-dimensionalviewpoint images based on a parallax amount corresponding to the userinstruction before the three-dimensional image is displayed so that thethree-dimensional object to be perceived by the user appears between thefront and back boundary positions selected by the user instruction. 9.The three-dimensional image displaying apparatus according to claim 1,wherein the information is depth information.
 10. A three-dimensionalimage displaying apparatus for displaying a three-dimensional imageperceived by one or more users based on two-dimensional viewpoint imagescorresponding respectively to right and left eyes of the one or moreusers, the apparatus comprising: a storage unit having pre-stored frontand back boundary positions of a three-dimensional object perceived bythe user, the front boundary position being a limit up to where thethree-dimensional object appears to be maximally close to the user andthe back boundary position being a limit up to where thethree-dimensional object appears to be maximally distant from the user;a receiving unit configured to receive a user instruction selectingfront and back boundary positions from the pre-stored front and backboundary positions; and a control unit configured to: receive a singletwo-dimensional image; generate the two-dimensional viewpoint imagesfrom the received single two-dimensional image; and adjust parallaxbetween or among the two-dimensional viewpoint images based on aparallax amount corresponding to the user instruction before thethree-dimensional image is displayed so that the three-dimensionalobject to be perceived by the user appears between the front and backboundary positions selected by the user instruction.
 11. The apparatusaccording to claim 10, wherein the parallax amount is stored in arecording area, and the control unit adjusts the parallax between oramong the two-dimensional viewpoint images based on the parallax amountin the recording area.
 12. The Three-dimensional image displayingapparatus according to claim 10, wherein the single two-dimensionalimage has information for generating the two-dimensional viewpointimages from the received single two-dimensional image, and the controlunit is further configured to generate the two-dimensional viewpointimages from the received single two-dimensional image based on thereceived information.
 13. The Three-dimensional image displayingapparatus according to claim 12, wherein the information is depthinformation.
 14. A three-dimensional image displaying apparatus fordisplaying a three-dimensional image perceived by one or more usersbased on two-dimensional viewpoint images corresponding respectively toright and left eyes of the one or more users, the apparatus comprising:a storage unit having pre-stored front and back boundary positions of athree-dimensional object perceived by the user, the front boundaryposition being a limit up to where the three-dimensional object appearsto be maximally close to the user and the back boundary position being alimit up to where the three-dimensional object appears to be maximallydistant from the user; a receiving unit configured to receive a parallaxamount representing a user's preference; and a control unit configuredto: receive a single two-dimensional image having information forgenerating the two-dimensional viewpoint images from the received singletwo-dimensional image; generate the two-dimensional viewpoint imagesfrom the received single two-dimensional image based on the receivedinformation; and adjust parallax between or among the two-dimensionalviewpoint images based on the parallax amount received by the receivingunit before the three-dimensional image is displayed so that thethree-dimensional object to be perceived by the user appears between thefront and back boundary positions.